NATURAL GAS SERVICES GROUP INC

Unless the context otherwise requires, references in this Annual Report on Form 10-K to Natural Gas Services Group, the Company, NGS, we, us, or our refer to Natural Gas Services Group, Inc. and its consolidated subsidiary, NGSG Properties, LLC. Certain specialized terms used in describing our natural gas compressor business are defined in Glossary of Industry Terms on page ii. Description of Business We were incorporated in December 1998 and initially operated as a holding company of a group of subsidiaries that were engaged in the manufacturing, operation and leasing of natural gas compression equipment, flares and related assets to the natural gas industry with a focus on unconventional natural gas production plays in the U.S. (such as coalbed methane, gas shales and tight gas). We completed our initial public offering in October 2002 and our common stock began trading on the American Stock Exchange under the symbol NGS. In October 2008, our common stock began trading on the New York Stock Exchange. Today, we are a premier provider of natural gas and electric compression equipment, technology and services to the energy industry. We rent, design, install, service and maintain natural gas engine and electric motor drive compressors for oil and gas production and processing facilities. We also provide aftermarket services in the form of call-out services on customer-owned equipment as well as commissioning of new units for customers.