The Tuskegee syphilis experiment was an infamous clinical study conducted between 1932 and 1972 by the U.S. Public Health Service to study the natural progression of untreated syphilis in rural African American men who thought they were receiving free health care from the U.S. government.

The Public Health Service started working with the Tuskegee Institute in 1932. Investigators enrolled in the study a total of 600 impoverished sharecroppers from Macon County, Alabama. 399 of those men had previously contracted syphilis before the study began, and 201 did not have the disease. The men were given free medical care, meals, and free burial insurance, for participating in the study. They were never told they had syphilis, nor were they ever treated for it. According to the Centers for Disease Control, the men were told they were being treated for “bad blood”, a local term for various illnesses that include syphilis, anemia, and fatigue.

http://en.wikipedia.org/wiki/Tuskegee_syphilis_experiment

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