Tuskegee syphilis experiment
For the study, researchers signed up a total of 600 African American men from Macon County, Alabama. A total of 399 of these men had syphilis before the study began. The remaining 201 did not have syphilis.  (In research, this healthy group is called a "control group"). Researchers wanted to compare the difference between people with and without syphilis. The men were given free health care, meals, and free burial insurance for being in the study.