Anteon Acquires Milestone Group.

FAIRFAX, Va. -- Anteon International Corporation (NYSE: ANT), a leading information technology, systems integration and engineering services company, announced today the acquisition of the Milestone Group, LLC, a high-end provider of IT professional services and solutions to key U.S. government clients. Anteon acquired Milestone Group for $31.5 million.

The acquisition supports Anteon's business strategy of closely aligning capabilities with the mission requirements of federal government customers and our national priorities. Milestone Group focuses its service offerings around three core competencies: Enterprise Architecture and Systems; Information Assurance; and Program and Financial Management. Milestone Group is particularly well positioned with the Missile Defense Agency (MDA) Directorates responsible for improving mission critical IT infrastructure and providing trusted network support services.

"We are extremely pleased to welcome Milestone Group to the Anteon team," said Joseph M. Kampf, Anteon President and CEO. "This acquisition demonstrates Anteon's commitment to bringing the best capabilities together in order to deliver comprehensive solutions to our customers. Milestone Group enjoys an excellent reputation in the market. They have a proven track record of providing trusted IT solutions to the Federal government and will specifically enhance the depth of our proven experience in joint missile defense programs, supporting the mission of MDA's leadership."

Milestone Group, a privately-held company headquartered in Arlington, VA, was founded in 1998. The majority of Milestone Group's revenue comes from work performed for the Missile Defense Agency, including enterprise-level program support at the Joint National Integration Center (JNIC) in Colorado Springs, CO. The remaining revenues are derived from a variety of customers including the Defense Information Systems Agency (DISA), the U.S. Army and the Federal Bureau of Investigation (FBI). Milestone Group has more than 120 employees at their headquarters and six other locations around the United States, with almost 90% of employees holding security clearances.

Milestone Group achieved revenues in excess of $21 million for the 12 months ended September 30, 2005. Anteon expects the transaction to be immediately accretive to earnings; however, given the timing and size of the transaction it is not expected to increase our earnings per share for 2005. Anteon will receive favorable tax benefits due to the acquisition of Milestone Group as an asset purchase. The anticipated financial results will be incorporated into Anteon's fourth quarter 2005 financial guidance, to be provided during the company's third quarter conference call on October 26, 2005.

"We are excited about the opportunities that joining Anteon will offer both our customers and our employees," Darrell Smith, Milestone Group CEO commented. "The addition of our engineering and IT capabilities will provide a great complement to many of Anteon's existing core areas of strength--Missile Defense program mission support, in particular."

Financial advisory services were provided to the members of Milestone Group, LLC by Legg Mason Wood Walker, Inc.

About Anteon

Anteon, headquartered in Fairfax, Virginia, is a leading information technology company serving the U.S. Federal government and international customers. Anteon designs, integrates, maintains, and upgrades state-of-the-art systems for national defense, intelligence, homeland security, and other high priority government missions. Anteon provides numerous government clients with the systems integration, strategy and program management, systems engineering, operations services, and simulation and training skills necessary to manage the development and operations of their mission critical systems. The Company was founded in 1976 and currently employs over 9,500 employees in more than 100 offices worldwide. Anteon consistently ranks among the top information technology integrators based on independent surveys, and has been named to the Forbes List of the 400 Best Big Companies in 2005, earning distinction on the Forbes Platinum List. Anteon is listed on the Standards & Poor's MidCap 400 Index. For more information, visit www.anteon.com.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995

The statements contained in this release which are not historical facts are forward-looking statements that are subject to risks and uncertainties that could cause actual results to differ materially from those set forth in, or implied by, forward-looking statements. The Company has tried, whenever possible, to identify these forward-looking statements using words such as "projects," "anticipates," "believes," "estimates," "expects," "plans," "intends," and similar expressions. Similarly, statements herein that describe the Company's business strategy, outlook, objectives, plans, intentions or goals are also forward-looking statements. The risks and uncertainties involving forward-looking statements include the Company's dependence on continued funding of U.S. government programs, government contract procurement and termination risks including risks associated with bid protests, and other risks described in the Company's Securities and Exchange Commission filings. These statements reflect the Company's current beliefs and are based upon information currently available to it. Be advised that developments subsequent to this release are likely to cause these statements to become outdated with the passage of time.