Between 1946 and 1948, the United States government carried out one of the most disturbing human experiments in modern history — in Guatemala.

Between 1946 and 1948, the United States government carried out one of the most disturbing human experiments in modern history — in Guatemala.

U.S.-funded researchers deliberately infected hundreds of Guatemalan people with sexually transmitted diseases, including syphilis, gonorrhea, and chancroid, without their knowledge or consent. The victims included soldiers, prisoners, sex workers, and patients in mental health institutions — some of the most vulnerable people in society.

The purpose of these experiments was to study whether penicillin could prevent or treat syphilis. To do this, researchers intentionally exposed subjects to disease through injections, contaminated materials, or sexual contact. Many participants were never properly treated, and several suffered lifelong health consequences or death.

These experiments were conducted secretly and hidden from the public for more than 60 years. They only came to light in 2010, when historical records revealed what had happened. That same year, the U.S. government officially acknowledged the experiments, and President Barack Obama issued a formal apology to Guatemala, calling the actions a serious violation of human rights.

This case is now widely cited as one of the most unethical medical experiments ever conducted, a reminder of how easily science can become abuse when ethics, consent, and human dignity are ignored.