The Tuskegee Syphilis Study began in 1932, when the Public Health Service enrolled hundreds of black males who were infected with syphilis. The purpose of the study was to observe the effects of the disease over time on untreated subjects. Despite positive findings in 1943 that penicillin was an acceptable treatment for syphilis, the researchers purposely withheld the antibiotic from their subjects. It was not until 1973 that the study was stopped, but many men had become ill, infected others, or died without being well informed of the risks and benefits of the study.