Laboratory Corporation of America Holdings, frequently known and referred to as LabCorp, is a United States S&P 500 company with its headquarters located in Burlington, North Carolina. LabCorp runs one of the largest clinical lab networks globally, with an American network consisting of 36 primary labs. Before the merger in 1995 with National Health Laboratory, LabCorp operated as Roche BioMedical. LabCorp does the most of its specialty testing at the Center for Esoteric Testing in Burlington, North Carolina. They also provide test services in three Canadian provinces and Puerto Rico and operate the National Genetics Institute in Los Angeles, California.