Tuskegee syphilis study, U.S. Public Health Service (PHS) study conducted from 1932 to 1972 in Macon county, Alabama, in which hundreds of Black men with syphilis were not adequately informed of their diagnosis and were denied effective treatment. The study became one of the most notorious examples of unethical human-subject research in American history and contributed to major reforms governing medical research and clinical trials. The project was designed to observe the effects of untreated...