Kforce Inc. (NASD: KFRC), a Tampa, Fla.-based professional staffing firm, is selling its Kforce Clinical Research Inc. division to inVentiv Health Inc. for $50 million in cash. The deal is expected to close by the end of the month.

The division posted revenue of $106.2 million in 2011. However, inVentiv is expecting annualized revenue of approximately $70 million. Kforce reported in its 10-K filing with the U.S. Securities and Exchange Commission that the division’s largest customer, which provided 50.5 percent of its revenue in 2011, plans to move its business to other suppliers by December 2012.

“As a result of an extensive review of our business and the changing landscape in the pharmaceutical industry, we have decided to sell our clinical research business,” said Kforce Chairman and CEO David Dunkel. “Selling this division is a logical step for us as we continue to narrow our focus, streamline our business mix and concentrate our resources on our core service offerings.”

InVentiv, a provider of clinical services and staffing, has more than 13,000 employees in 40 countries. It is owned by inVentiv Group Holdings Inc., an organization affiliated with Thomas H. Lee Partners LP, a Boston-based private equity firm.

“With its strong clinical monitoring expertise, a customer-focused approach and an impressive portfolio of clients, Kforce Clinical Research is an attractive complement to inVentiv’s existing services,” said inVentiv CEO Paul Meister.