The researchers’ true objective was to understand the long-term health effects of untreated syphilis. The Public Health Service continued to run the study even after 1947, when penicillin proved to be an effective treatment for syphilis. By the time the experiment ended in 1972 due to public outrage, 128 patients had died of syphilis or its complications.
In 1932, 600 African American men in Alabama took part in a medical study on syphilis, a sexually transmitted disease caused by bacteria. U.S. Public Health Service researchers told the participants—both with and without syphilis—that they were being treated for “bad blood,” a catch-all term for various ailments. But unbeknownst to them, some participants were denied any treatment at all.