The study enrolled 399 men with syphilis and 201 without it. Researchers told them they were being treated for "bad blood" and offered free meals, medical exams and burial insurance. The men did not give informed consent. Researchers worked to keep them from getting penicillin elsewhere. Many men died of syphilis or its complications, and some wives and children were infected.
A Public Health Service employee, Peter Buxtun, raised concerns, and an Associated Press story in July 1972 exposed the study. It ended that year. A 1974 settlement paid survivors and heirs, and the government provided lifetime medical care. President Bill Clinton issued a formal apology in 1997.
The study led to the National Research Act of 1974 and new rules for informed consent and ethics review of research. Researchers have linked its disclosure to lower trust in medicine among Black men. It is often cited in discussions of medical racism.