The Tuskegee Syphilis Study was a notorious unethical medical experiment conducted by the U.S. Public Health Service between 1932 and 1972 in Tuskegee, Alabama. The study aimed to observe the natural progression of untreated syphilis in African American men. The participants were told they were receiving free healthcare, when in fact they were left untreated, even after penicillin became a widely available and effective treatment for syphilis.

The study violated ethical standards by failing to provide informed consent, deceiving participants about the true nature of the study, and continuing to withhold treatment even when it was known to be effective. As a result, many men suffered severe health consequences, including blindness, mental illness, and death.

The study's exposure in the early 1970s led to major reforms in biomedical research ethics, including the establishment of Institutional Review Boards to ensure the protection of human research subjects. The Tuskegee Syphilis Study remains a dark chapter in American history, highlighting the systemic racism and mistreatment of African Americans in the medical field.