The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the Centers for Disease Control and Prevention (CDC) within the U.S. Department of Health and Human Services. Despite its name, it is not part of the National Institutes of Health. Its current director is John Howard.

NIOSH is headquartered in Washington, D.C., with research laboratories and offices in Cincinnati, Ohio; Morgantown, West Virginia; Pittsburgh, Pennsylvania; Denver, Colorado; Anchorage, Alaska; Spokane, Washington; and Atlanta, Georgia. NIOSH is a professionally diverse organization with a staff of 1,200 people representing a wide range of disciplines including epidemiology, medicine, industrial hygiene, safety, psychology, engineering, chemistry, and statistics.

The Occupational Safety and Health Act, signed by President Richard M. Nixon on December 29, 1970, created both NIOSH and the Occupational Safety and Health Administration (OSHA). NIOSH was established to help ensure safe and healthful working conditions by providing research, information, education, and training in the field of occupational safety and health. NIOSH provides national and world leadership to prevent work-related illness, injury, disability, and death by gathering information, conducting scientific research, and translating the knowledge gained into products and services. Although NIOSH and OSHA were established by the same Act of Congress, the two agencies have distinct and separate responsibilities. NIOSH has several “virtual centers” through which researchers at its geographically dispersed locations are linked by shared computer networks and other technologies that stimulates collaboration and helps overcome the challenges of working as a team across distances.