Nontuberculous mycobacterial (NTM) diseases are less common than tuberculosis (TB), but in the last 2 to 3 decades there has been a significant increase in the incidence of both pulmonary and extrapulmonary diseases caused by these organisms. Runyon (1959) classified NTM into four groups based on the rate of growth and pigment production. These organisms are found throughout the environment and have been isolated from water, soil, milk, fish, birds and animals. Various species of NTM can be differentiated on the basis of biochemical characteristics, lipid pattern of their cell walls, molecular methods, etc. Prevention of health-care related NTM infections requires that surgical wounds, injection sites and intravenous catheters not be exposed to tap water or tap water-derived fluids.