The Tuskegee syphilis experiment (also known as the Tuskegee syphilis study or Public Health Service syphilis study) was an infamous clinical study conducted between 1932 and 1972 in Tuskegee, Alabama by the U.S. Public Health Service to study the natural progression of untreated syphilis in poor, rural black men who thought they were receiving free health care from the U.S. government.

The Public Health Service, working with the Tuskegee Institute, began the study in 1932. Investigators enrolled in the study a total of 600 impoverished, African-American sharecroppers from Macon County, Alabama; 399 who had previously contracted syphilis before the study began, and 201 without the disease. For participating in the study, the men were given free medical care, meals, and free burial insurance. They were never told they had syphilis, nor were they ever treated for it. According to the Centers for Disease Control, the men were told they were being treated for "bad blood," a local term used to describe several illnesses, including syphilis, anemia and fatigue.