Nontuberculous mycobacteria are identified in almost half of the cultures reported positive for mycobacteria in clinical laboratories in the United States. While many represent saprophytic colonization or laboratory contamination, a significant number of these organisms are the agents of disease. Such organisms can be the cause of pulmonary, soft tissue, cutaneous and lymphatic infections, keratitis, osteomyelitis, postsurgical infection, endocarditis and disseminated disease.