Press release

MTS Announces an ADR Ratio Change

April 20, 2010

Moscow, Russian Federation – Mobile TeleSystems OJSC (“MTS” – NYSE: MBT), the leading telecommunications provider in Russia and the CIS, announces that it will be changing its current American Depositary Receipt (ADR) ratio effective May 3, 2010.

The ratio will change from the current 1 ADR per 5 common shares to 1 ADR per 2 common shares. Existing ADRs will continue to be valid and will not have to be exchanged for new ADRs. The number of underlying common shares will remain unchanged.

To implement the change, MTS ADR holders of record at the close of business on April 28, 2010, will receive 1.5 ADRs for each ADR held. Additional ADRs are expected to be distributed on or around April 30, 2010, the ADR payment date.

Commenting on the ADR ratio change, Mikhail Shamolin, President and CEO of MTS, said: “MTS’ ADR price has increased more than 60% since the Company’s last effective stock split in January 2005. Changing the ADR ratio will bring the price more in line with our peer companies and support liquidity. We feel this will allow our ADRs to appeal to a broader investor base and provide additional flexibility to current shareholders in managing their portfolios.”

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For further information, please contact in Moscow:

Joshua B. Tulgan

Director, Investor Relations

Mob: +7 985 220 4208

Department of Investor Relations

Mobile TeleSystems OJSC

Tel: +7 495 223 2025

E-mail: ir@mts.ru

Learn more about MTS. Visit the official blog of the Investor Relations Department at www.mtsgsm.com/blog/

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Mobile TeleSystems OJSC (“MTS”) is the leading telecommunications group in Russia, Eastern Europe and Central Asia, offering mobile and fixed voice, broadband, pay TV as well as content and entertainment services in one of the world’s fastest growing regions. Including its subsidiaries, the Group services over 102.3 million mobile subscribers in Russia, Ukraine, Uzbekistan, Turkmenistan, Armenia and Belarus, a region that boasts a total population of more than 230 million. Since June 2000, MTS’ Level 3 ADRs have been listed on the New York Stock Exchange (ticker symbol MBT). Additional information about the MTS Group can be found at www.mtsgsm.com.

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Some of the information in this press release may contain projections or other forward-looking statements regarding future events or the future financial performance of MTS, as defined in the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. You can identify forward looking statements by terms such as “expect,” “believe,” “anticipate,” “estimate,” “intend,” “will,” “could,” “may” or “might,” and the negative of such terms or other similar expressions.  We wish to caution you that these statements are only predictions and that actual events or results may differ materially. We do not undertake or intend to update these statements to reflect events and circumstances occurring after the date hereof or to reflect the occurrence of unanticipated events. We refer you to the documents MTS files from time to time with the U.S. Securities and Exchange Commission, specifically the Company’s most recent Form 20-F. These documents contain and identify important factors, including those contained in the section captioned “Risk Factors” that could cause the actual results to differ materially from those contained in our projections or forward-looking statements, including, among others, the severity and duration of current economic and financial conditions, including volatility in interest and exchange rates, commodity and equity prices and the value of financial assets; the impact of Russian, U.S. and other foreign government programs to restore liquidity and stimulate national and global economies, our ability to maintain our current credit rating and the impact on our funding costs and competitive position if we do not do so, strategic actions, including acquisitions and dispositions and our success in integrating acquired businesses, including Comstar-UTS, potential fluctuations in quarterly results, our competitive environment, dependence on new service development and tariff structures, rapid technological and market change, acquisition strategy, risks associated with telecommunications infrastructure, governmental regulation of the telecommunications industries and other risks associated with operating in Russia and the CIS, volatility of stock price, financial risk management and future growth subject to risks.

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MOBILE TELESYSTEMS OJSC

By:

/s/ Mikhail Shamolin

Name:

Mikhail Shamolin

Title:

CEO

Date:   April 20, 2010