BURLINGTON, N.C. — Laboratory Corporation of America is filling the ranks of chief executive officer with an insider when current CEO Thomas Mac Mahon retires on Jan. 1 of next year.

Named to take the top spot is David King, the current chief operating officer. King, who joined LabCorp (NYSE: LH) in 2001 after working for the international testing services provider as outside counsel. He has been COO and executive vice president since 2005. His first position with the company was general counsel and chief compliance officer.

King also will join LabCorp’s board on directors.

Mac Mahon, the company’s CEO the past 10 years, will remain chairman of the board until the company’s shareholders meeting in 2008.

‘Working closely with Dave King over the past several years has convinced me that he is the right executive to lead LabCorp into the future,” Mac Mahon said in a statement. “Over the past several years, Dave has led the effort to update and implement our successful strategic plan by focusing on expanding our managed care relationships and furthering our scientific leadership with a concentration on our cancer testing offerings.”

LabCorp employs some 24,000 people and had $3.3 billion in revenues in 2005.

LabCorp: www.labcorp.com