Syphilis was a major public health problem in the 1920s, and in 1928 the Julius Rosenwald Fund, a charity organization, launched a public healthcare project for blacks in the American rural south. Sounds good, right? It was, until the Great Depression rocked the U.S. in 1929 and the project lost its funding. Changes were made to the program; instead of treating health problems in underserved areas, in 1932 poor black men living in Macon County, Alabama, were instead enrolled in a program to treat what they were told was their "bad blood" (a term that, at the time, was used in reference to everything from anemia to fatigue to syphilis). They were given free medical care, as well as food and other amenities such as burial insurance, for participating in the study. But they didn't know it was all a sham. The men in the study weren't told that they were recruited for the program because they were actually suffering from the sexually transmitted disease syphilis, nor were they told they were taking part in a government experiment studying untreated syphilis, the "Tuskegee Study of Untreated Syphilis in the Negro Male." That's right: untreated.
Despite thinking they were receiving medical care, subjects were never actually properly treated for the disease. This went on even after penicillin hit the scene and became the go-to treatment for the infection in 1945, and after Rapid Treatment Centers were established in 1947. Despite concerns raised about the ethics of the Tuskegee Syphilis Study as early as 1936, the study didn't actually end until 1972 after the media reported on the multi-decade experiment and there was subsequent public outrage.