The Tuskegee Study of Untreated Syphilis in the Negro Male (informally referred to as the Tuskegee Experiment or Tuskegee Syphilis Study) was a study conducted between 1932 and 1972 by the United States Public Health Service (PHS) and the Centers for Disease Control and Prevention (CDC) on a group of nearly 400 African American men with syphilis as well as a control group without.

https://en.wikipedia.org/wiki/Tuskegee_Syphilis_Study