Dear Shareholder,

We present this Semi-Annual Report which covers the activities of Aberdeen Asia-Pacific Income Fund, Inc. (the “Fund”) for the six-month period ended April 30, 2018. The Fund’s principal investment objective is to seek current income. The Fund may also achieve incidental capital appreciation.

Fund Updates

As of September 30, 2017, the Fund’s blended benchmark changed, as summarized below:

Total Investment Return

For the six-month period ended April 30, 2018, the total return to shareholders of the Fund based on the net asset value (“NAV”) and market price of the Fund are as follows:

The Fund’s NAV total return is based on the reported NAV on each financial reporting period end which could differ from the NAV disclosed within the financial statements.

NAV, Share Price and Discount

The below table represents comparison from current year to prior year of Market Price to NAV and associated Premium / Discount.

Portfolio Allocation

As of April 30, 2018, the Fund held 59.6% of its total investments in Asian debt securities, 32.9% in Australian debt securities, 5.0% in European debt securities, 2.2% in U.S. debt securities and 0.3% in developed Middle East debt securities.

Of the Fund’s total investments, excluding hedges, 36.9% were held in U.S. Dollar denominated bonds issued by foreign issuers. The rest of the Fund’s currency exposure was 35.5% in the Australian Dollar and 27.6% in various Asian currencies.

Of the Fund’s total investments, including hedges, 36.8% were held in U.S. Dollar denominated bonds issued by foreign issuers. The rest of the Fund’s currency exposure was 30.8% in the Australian Dollar and 32.4% in various Asian currencies.

Credit Quality

As of April 30, 2018, 45.1% of the Fund’s total investments were invested in securities where either the issue or the issuer was rated A or better by Standard & Poor’s* or Moody’s Investors Services, Inc. (“Moodys”).**

Portfolio Management

The Fund is managed by Aberdeen’s Asia-Pacific fixed income team. The Asia-Pacific fixed income team works in a truly collaborative fashion; all team members have both portfolio management and research responsibilities. The team is responsible for the day-to-day management of the Fund.

Managed Distribution Policy

Distributions to common shareholders for the twelve-month period ended April 30, 2018 totaled $0.42 per share. Based on the share price of $4.57 on April 30, 2018, the distribution rate over the twelve-month period ended April 30, 2018 was 9.2%. Since all distributions are paid after deducting applicable withholding taxes, the effective distribution rate may be higher for those U.S. investors who are able to claim a tax credit.

On May 9, 2018 and June 11, 2018, the Fund announced that it will pay on May 31, 2018 and June 29, 2018, respectively, a distribution of U.S. $0.035 per share to all shareholders of record as of May 23, 2018 and June 21, 2018, respectively.

The Fund’s policy is to provide investors with a stable monthly distribution out of current income, supplemented by realized capital gains and, to the extent necessary, paid-in capital, which is a non-taxable return of capital. This policy is subject to an annual review as well as regular review at the Board’s quarterly meetings, unless market conditions require an earlier evaluation.

Fund’s Leverage

The table below summarizes certain key terms of the Fund’s current leverage:

The Series A Mandatory Redeemable Preferred Shares, with a liquidation value of $50 million, are rated AA by Fitch Ratings³ and

the combined $350 million 7-year, 10-year and 15-Year Series A, B, C and D Senior Secured Notes are rated AAA by Fitch Ratings.

We believe the Fund has been able to lock in an attractive rate cost of borrowing and extend the maturity of the leverage facility while diversifying its borrowing structure during what we believe to be a favorable current interest rate environment. A more detailed description of the Fund’s leverage can be found in the Report of the Investment Manager and the Notes to Financial Statements.

Open Market Repurchase Program

The Fund’s policy is generally to buy back Fund shares on the open market when the Fund trades at certain discounts to NAV and management believes such repurchases may enhance shareholder value. During the six-month period ended April 30, 2018 and fiscal year ended October 31, 2017, the Fund repurchased 200,000 and 1,135,695 shares, respectively.

Portfolio Holdings Disclosure

The Fund’s complete schedule of portfolio holdings for the second and fourth quarters of each fiscal year are included in the Fund’s semi-annual and annual reports to shareholders. The Fund files its complete schedule of portfolio holdings with the Securities and Exchange Commission (the “SEC”) for the first and third quarters of each fiscal year on Form N-Q. The Fund’s Form N-Q filings are available on the SEC’s website at http://www.sec.gov and may be reviewed and copied at the SEC’s Public Reference Room in Washington, D.C. Information about the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330. The Fund makes the information on Form N-Q available to shareholders on the Fund’s website or upon request and without charge by calling Investor Relations toll-free at 1-800-522-5465.

Proxy Voting

A description of the policies and procedures that the Fund uses to determine how to vote proxies relating to portfolio securities, and information regarding how the Fund voted proxies relating to portfolio securities during the most recent twelve months ended June 30 is available by August 31 of the relevant year: (i) upon request and without charge by calling Investor Relations toll-free at 1-800-522-5465; and (ii) on the SEC’s website at http://www.sec.gov.

Unclaimed Share Accounts

Please be advised that abandoned or unclaimed property laws for certain states require financial organizations to transfer (escheat) unclaimed property (including Fund shares) to the state. Each state has its own definition of unclaimed property, and Fund shares could be considered “unclaimed property” due to account inactivity (e.g., no owner-generated activity for a certain period), returned mail (e.g.,

when mail sent to a shareholder is returned to the Fund’s transfer agent as undeliverable), or a combination of both. If your Fund shares are categorized as unclaimed, your financial advisor or the Fund’s transfer agent will follow the applicable state’s statutory requirements to contact you, but if unsuccessful, laws may require that the shares be escheated to the appropriate state. If this happens, you will have to contact the state to recover your property, which may involve time and expense. For more information on unclaimed property and how to maintain an active account, please contact your financial adviser or the Fund’s transfer agent.

Investor Relations Information

As part of Aberdeen’s commitment to shareholders, we invite you to visit the Fund on the web at www.aberdeenfax.com. Here, you can view monthly fact sheets, quarterly commentary, distribution and performance information, updated daily fact sheets courtesy of Morningstar^®, portfolio charting and other Fund literature.

Enroll in our email services today and be among the first to receive the latest closed-end fund news, announcements, videos and information. In addition, you can receive electronic versions of important Fund documents including annual reports, semi-annual reports, prospectuses, and proxy statements. Sign up today at cef.aberdeen-asset.us/en/cefinvestorcenter/contact-us/email.

Contact Us:

Yours sincerely,

/s/ Christian Pittard

Christian Pittard

President

Market review

There was a distinct transition in risk sentiment in the Asian fixed-income markets during the six-month period ended April 30, 2018. Over the first half of the period to the end of January 2018, Asian bonds were relatively stable, while currencies appreciated significantly against the U.S. dollar. Emerging-market sovereign spreads in January hit their tightest levels since 2014, while Asian investment-grade¹ corporate bond spreads reached their tightest levels since before the global financial crisis, as markets were supported by robust flows. Given the heavier positioning across markets, investor sentiment became vulnerable to several risks. The U.S. Federal Reserve (Fed) continued to raise the federal funds rate as expected, resulting in the two-year U.S. Treasury yield rising by about 90 basis points (bps) over the reporting period and the 10-year yield breaching 3% towards the end of April 2018. Concerns over the potential for a full-blown trade war between the U.S. and China weighed on investor sentiment, while worries over the U.S.’s withdrawal from the Iran nuclear deal raised geopolitical tensions in the Middle East and helped drive another surge in the Brent crude oil price, which neared US$75 per barrel at the end of the reporting period.

Asia-Pacific government bond yields generally rose over the reporting period, particularly in the second half and in April 2018. Several Asian central banks also raised their policy rates during the period, including Malaysia and South Korea, with the Philippines and Indonesia following suit soon after the end of the reporting period in May 2018, given firm growth and rising external inflation risks. While regional currencies generally exhibited better stability than their G10² and broader emerging-market counterparts, they depreciated in the final three months of the period, surrendering some earlier gains.

However, most Asian bond markets delivered positive total returns over the reporting period, and the majority of regional currencies ended firmer against the U.S. dollar. Notably, Chinese bonds posted solid performance as yields continued to move lower, benefiting from the market’s inclusion in the Bloomberg Barclays global bond indices. China, Malaysia, Thailand and South Korea, also have current account surpluses, and these markets outperformed their regional peers. All four markets saw robust currency appreciation over the reporting period, with the Malaysia ringgit, Thai baht, Korean won and Chinese yuan ending the reporting period up 7.9%, 5.3%, 4.9% and 4.8%, respectively, against the U.S. dollar. Indonesian bonds

were buoyed by their induction into the Bloomberg Barclays bond indices, but the Indonesian rupiah’s weakness pared the gains. Sri Lankan bonds benefited from the country’s improving fiscal management, but the Sri Lankan rupee’s decline trimmed the total returns. The Singapore dollar’s strength aided Singapore bond market returns, even though yields tracked U.S. Treasuries higher. Conversely, the Philippine and Indian markets lagged their peers. The former market was hampered by relatively weak bond performance and the latter by underperformance in the Indian rupee, which depreciated by 2.9% against the U.S. dollar over the period.

Regional credit markets moved lower on a total-return basis over the reporting period, mainly because of relative weakness in U.S. Treasuries. Investment-grade credits underperformed high-yield issues. Spreads in the investment-grade segment widened by 20 bps in the final three months and nearly 10 bps over the full reporting period, while high-yield spreads ended the period only marginally wider. At the sector level, technology credits were among the biggest market laggards as several Chinese companies were targeted in the China-U.S. trade spat. Consumer-sector credits were also not spared amid fears that global trade would be hurt. Despite higher energy prices, oil-and-gas credits weakened. The highly leveraged utility sector was hampered by the prospect of rising borrowing costs. Scandals at several Chinese and Indian banks hurt investor sentiment in the financial sector, while ongoing deleveraging and property curbs in mainland China weighed on infrastructure-related credits.

Fund performance review

The Fund returned -1.14% on a net asset value basis for the six-month period ended April 30, 2018, versus the -0.73% return of its blended benchmark.³ The Fund’s strategies in Asian U.S. dollar-denominated credit and Australian bonds detracted from absolute performance as both market segments declined during the period. However, the Fund’s underweight allocations to these sectors bolstered relative performance.

Asian local-currency bonds recorded positive absolute returns for the reporting period but the Fund’s exposure to the sector did not have a significant impact on relative performance. The Fund’s overweight positions in Indonesia and Sri Lanka contributed to both absolute and relative performance as these markets performed well during the period. However, weakness in the Indonesian rupiah and Sri Lankan

rupee reduced these gains. An overweight position in Indian bonds hurt the Fund’s relative performance as the market declined, exacerbated by the Indian rupee’s weakness. The Fund’s overweight exposure to Asian local-currency high-yield bonds relative to its blended benchmark detracted from absolute and relative performance, attributable mainly to negative duration⁴ effects in Indonesia.

We have positioned the Fund for many of the more acute risks that the Asian markets face. Specifically, the Fund has had very little exposure to markets with higher correlations to U.S. Treasuries such as Hong Kong and Singapore, reducing the impact from rising interest rates, or the Philippines which for domestic reasons has been among the weakest-performing markets. We have used futures to hedge U.S. interest-rate risk and swaps⁵ to lock in the cost of leverage. We also have employed hedges on the Australian dollar. We have sought more idiosyncratically driven and resilient fixed-income markets such as China, which recently has outperformed the overall Asia-Pacific region. With the capital market expanding, we believe that there is scope to add to the Fund’s positions in China. Furthermore, we have initiated positions in what we view as out-of-favor markets such as Sri Lanka, which benefited Fund performance over the reporting period.

As recently as April 2018, Indonesia and several other countries, including the Philippines and India, were still seeing upgrades by the credit-rating agencies. China, Malaysia, Thailand and Singapore run current account surpluses. During the heightened market volatility over the last several months of the reporting period, their respective currencies, to which the Fund has exposure, generally outperformed those of other emerging markets as well as many developed countries. India has very little U.S. dollar-denominated debt; indeed, the government does not issue sovereign debt. Indonesia has some of the lowest debt levels of any country in the world, with a debt to gross domestic product (GDP) ratio of roughly 25%. The fiscal deficit is capped by law at 3% of GDP, but is typically comfortably below that.

With robust and improving fundamentals, we believe that there is opportunity in the Asian fixed-income market. Consequently, we decreased the Fund’s holdings in relatively more defensive credits in Australia and added credit risk in that market, while we also reduced hedging of the Australian dollar. We also rotated out of some of the more defensive positions in the Asian credit markets. In the

Indonesian local currency market, the five- to twenty-year yield curve widened to a multi-year high–with essentially no deterioration in fundamentals and the central bank already raising interest rates. Therefore, we extended the Fund’s duration in Indonesia. Shortly after the end of the reporting period, we increased the Fund’s duration in Malaysia given domestic factors centered on the surprising results of the country’s parliamentary election, with longer-dated yields rising to levels that typically see strong domestic support. We also extended the Fund’s duration and rotated out of some more defensive credit holdings in the Chinese market.

The overall impact on relative performance from the Fund’s use of derivatives, excluding leverage, was generally positive, driven by the currency overlay⁶ into Asian currencies, and the hedging of both Australian dollar risk and U.S. Treasury risk. However, the impact of leverage applied at the total portfolio level was negative, factoring in negative bond and currency performance, particularly in the final three months of the reporting period, and the cost of leverage.

Outlook

Over the past several months, the global market environment has been hit by negative investor sentiment driven to a large degree by geopolitical risks and uncertainty over potential outcomes. Instability in the Middle East and doubts about the U.S. withdrawal from the Iran nuclear deal are being reflected in volatile oil prices. Stronger commodity prices typically have benefited most emerging markets and countries such as Australia, particularly in an environment where global economic growth is improving. However, for now, even commodity exporters are underperforming. Similarly, the threat of a global trade war has hurt market sentiment, although with rhetoric from key political leaders changing on a weekly basis, we believe that it is difficult to forecast the economic impact. In our view, investors ultimately will need clarity on policies, but in the meantime, the tendency has been towards pricing in the worst-case outcomes.

For the most part, economic and corporate performance has remained positive. Firm global and regional demand has supported exports and production as well as the technology cycle, which has benefited Asia. Domestic demand in the Asia-Pacific region has remained resilient, supporting improvement in earnings. We believe that fiscal consolidation generally remains on track. China is focused on reining in its excesses; while that could slow growth, it has also resulted in capacity reductions that have benefited other emerging-

market producers. In Asia, several countries, including India, Indonesia, Philippines and Vietnam, have seen ratings upgrades in recent years, and the outlook remains positive, with the Asia-Pacific region benefiting from positive political transitions and reform, in our view. Flows into emerging markets and Asia over the last two years have been strong, following the shocks that hit the region in the prior years. Therefore, we believe it is possible that global investors have been primed for negative news. Market concerns are varied, including the cost of financing external debt as the U.S. dollar appreciates; the ballooning fiscal deficit in the U.S.; weaker demand as exports suffer from escalating trade conflict; and the potential for a policy-induced economic slowdown in China. Additionally, we believe that Asia is more vulnerable to the rise in commodity prices, including oil, given its status as a net oil importer. For a country such as India, higher commodity prices comprise one of the bigger risks. Nonetheless, markets have a tendency to overreact, so whether these concerns materialize is anyone’s guess, in our opinion.

We anticipate that major global central banks may continue normalizing interest rates, led by the Fed. In our view, this should drive short-dated yields higher. However, Fed rate hikes and rising U.S. Treasury yields have been forecast so well, we do not believe that the increases should surprise investors. The Fed is normalizing monetary policy because U.S. and global economic growth is improving, which historically has been positive for emerging markets and Asia, as we have seen in the recovery in exports. Notably, in our view, the Fed increased its benchmark interest rate by more than 400 bps over the previous monetary policy tightening cycle from 2004 to 2006. However during that period the U.S. dollar sold off and emerging-market and Asian currencies performed well. A strengthening global economy historically has been supportive for Asian exports and the technology sector. We believe that these conditions comprise a favorable backdrop for the Asian markets.

Outside of the U.S., we believe that there will be gradual policy tightening, given the risks we cited previously. Some central banks in Asia, such as South Korea, the Philippines, Malaysia and Indonesia, have already commenced gradual rate hikes, with India likely to follow in the coming quarters, in our view, even though inflation remains relatively stable.

Our credit strategy remains defensive. We prefer companies that, in our view, have conservative capital structures, balance-sheet strength and cash-flow generation. We also like Chinese and Hong Kong property credits because we believe that they have good execution and sizeable, high-quality land banks,⁷ although we prefer

to position the Fund in shorter-dated debt, given our anticipation of greater supply in this segment. Overall, while we intend to maintain the Fund’s underweight allocation to commodities, we could make exceptions for companies that we believe have robust business models and improving debt levels. We see the widening in spreads as a healthy correction, which may present opportunities for us to add to holdings in issues that were previously too pricey. Yields on 10-year U.S. Treasuries have already moved towards upside forecasts of 3.25%, which in our view suggests the underlying drag from rising U.S. yields has been priced in to a great degree. In the near term, we believe that further spread-widening is likely, although we are generally seeing opportunities to increase risk.

In Australia, unemployment has remained stubbornly high, with weakness in the housing market dampening inflation and credit growth. We believe that improving employment could begin to reverse these dynamics in the first half of 2019. However, in the medium term, we believe that this backdrop creates an outlook for yields to remain broadly stable, with domestic economic and inflation softness counterbalancing further rate hikes in the U.S. For the Australian dollar, net non-resident financial flows remain at the highest level since 2015. Global demand, firm commodity markets and a stable economy in China are all positive for the currency. However, the broad appreciation of the U.S. dollar and the Australian dollar’s higher volatility has driven notable weakness in the currency. The relationship to typical benchmarks of risk or demand, such as equities (i.e., the Standard & Poor’s 500 Index⁸) and commodities has, at least in the near term, foundered, with the currency overshooting on the downside to levels far below longer-term moving averages seen during some of the heavy sell-offs in 2016. Indeed, the Australian dollar has traded closer to levels in our estimated worst-case scenario,⁹ prompting us to reduce the Fund’s hedges.

Loan Facilities and the Use of Leverage

The amounts borrowed under the Revolving Credit Facility, the Term Loan Facility, the Notes and the Series A MRPS (each as defined below) may be invested to seek to return higher rates than the rates pursuant to which interests or dividends are paid under such forms of leverage. However, the cost of leverage could exceed the income earned by the Fund on the proceeds of such leverage. To the extent that the Fund is unable to invest the proceeds from the use of leverage in assets which pay interest at a rate which exceeds the rate paid on the leverage, the yield on the Fund’s common stock will decrease. In addition, in the event of a general market decline in the value of assets in which the Fund invests, the effect of that decline

will be magnified in the Fund because of the additional assets purchased with the proceeds of the leverage.

The Fund employed leverage obtained via bank borrowing and other forms of leverage during the reporting period. On August 10, 2017, the Fund entered into a note purchase agreement with institutional investors relating to the private placement of $100 million of Series D senior secured notes rated ‘AAA’ by Fitch Ratings. Net proceeds of the Series D notes were used to pay down $100 million of the Fund’s existing 5-year Term Loan A originally maturing on June 12, 2018 (the “Term A Facility”). On February 8, 2017, the Fund entered into a note purchase agreement with institutional investors relating to the private placement of $50 million of Series C senior secured notes rated ‘AAA’ by Fitch Ratings. Net proceeds of the Series C notes were used to refinance $50 million of the Fund’s existing syndicated revolving credit facility (the “Revolving Credit Facility”). On April 7, 2017, the Fund renewed its $100 million Revolving Credit Facility for a 3-year period with a syndicate of banks. On June 12, 2013, the Fund entered into a note purchase agreement with institutional investors relating to the private placement of $200 million of Series A and Series B senior secured notes rated `AAA’ by Fitch Ratings, $100 million due June 12, 2020 and $100 million due June 12, 2023 (the “Notes”). On the same day, the Fund also entered into a term loan agreement providing for $200 million in secured term loans from Bank of America, N.A., $100 million due June 12, 2016 (on December 14, 2015, the maturity of this loan was extended to December 14, 2019) and $100 million due June 12, 2018 (the “Term Loan Facility”), which was refinanced as outlined above. On June 27, 2013, the Fund issued a private offering of 2 million shares of Series A Mandatory Redeemable Preferred Shares due June 25, 2023 (the “Series A MRPS”). The Series A MRPS have a liquidation value of $50 million and are rated ‘AA’ by Fitch Ratings. The Fund’s outstanding balance as of April 30, 2018 was $100 million on the Revolving Credit Facility.

The Fund’s leveraged capital structure creates special risks not associated with unleveraged funds having similar investment objectives and policies. The funds borrowed pursuant to the Revolving Credit Facility, the Term Loan Facility and the Notes may constitute a substantial lien and burden by reason of their prior claim against the income of the Fund and against the net assets of the Fund in liquidation. The Fund is limited in its ability to declare dividends or other distributions under the terms of the various forms of leverage. In the event of an event of default under either the Revolving Credit Facility or Term Loan Facility, the lenders have the right to cause a liquidation of the collateral (i.e., sell portfolio securities and other assets of the Fund) and, if any such default is not cured, the lenders may be able to control the liquidation as well. In the event of an event of default under the Note Purchase Agreement, the holders of the Notes

have the right to cause a liquidation of the collateral (i.e., cause the sale of portfolio securities and other assets of the Fund).

Each of the Revolving Credit Facility Agreement, the Term Loan Agreement, the Note Purchase Agreement, and the Securities Purchase Agreement relating to the Series A MRPS includes usual and customary covenants for the applicable type of transaction. These covenants impose on the Fund asset coverage requirements, Fund composition requirements and limits on certain investments, such as illiquid investments, which are more stringent than those imposed on the Fund by the 1940 Act. The covenants or guidelines could impede the Fund’s investment manager, investment adviser, or sub-adviser from fully managing the Fund’s portfolio in accordance with the Fund’s investment objective and policies. Furthermore, non-compliance with such covenants or the occurrence of other events could lead to the cancellation of any and/or all of the forms of leverage. As of April 30, 2018, the Fund was in compliance with all covenants under the agreements relating to the various forms of leverage.

Interest Rate Swaps

The Fund may enter into interest rate swaps to manage interest rate exposure and hedge interest rate risk. As of April 30, 2018, the Fund held interest rate swap agreements with an aggregate notional amount of $100 million, which represented 100% of the Fund’s Revolving Credit Facility. Under the terms of the agreements currently in effect, the Fund receives a floating rate of interest (three-month USD-LIBOR BBA rate) and pays fixed rates of interest for the terms and based upon the notional amounts set forth below:

A significant risk associated with interest rate swaps is the risk that the counterparty may default or file for bankruptcy, in which case the Fund would bear the risk of loss of the amount expected to be received under the swap agreements. There can be no assurance that the Fund will have an interest rate swap in place at any given time nor can there be any assurance that, if an interest rate swap is in place, it will be successful in hedging the Fund’s interest rate risk with respect to the loan facility. The implementation of this strategy is at the discretion of the Leverage Committee of the Board.

Aberdeen Asset Management Asia Limited