The Tuskegee syphilis study was a controversial clinical study conducted between 1932 and 1972 in the United States. It involved 399 African American men with untreated syphilis and 201 men without the disease. The study aimed to observe the natural progression of syphilis without providing proper treatment, even after penicillin became a standard cure in the 1940s. Participants were misled about their health status and were not informed about the true purpose of the study. This unethical research raised significant ethical concerns and led to changes in laws and regulations regarding human subjects in research, including the establishment of the Belmont Report.