The United States Army Medical Research Institute of Infectious Diseases (USAMRIID, pronounced you-SAM-rid) is a military research institute for medicine based at Fort Detrick, Frederick, Maryland used for research of infectious disease that may have defensive applications against biological warfare that would protect the citizens of the United States. Colonel George W. Korch is the current commander.

USAMRIID was for a time the only United States Department of Defense laboratory equipped to study highly hazardous viruses at Biosafety Level 4. There is another at the National Naval Medical Center currently.

USAMRIID is a critical resource for the Army, the Department of Defense, and the United States. It has award-winning military and civilian scientists, highly trained support personnel, and unique, state-of-the-art research facilities. Investigators at the facilities contribute to advances in scientific knowledge and collaborate with the Centers for Disease Control and Prevention, the World Health Organization, and academic centers of excellence worldwide.

The research institute was the first bio-facility of its type to research the Ames strain of anthrax, determined through genetic analysis to be the bacterium used in the 2001 anthrax attacks.