ABC News' Dr. Richard Besser, a former acting director of the Centers for Disease Control and Prevention, said both experiments were highly unethical.
"I think there's absolutely no difference between the Tuskegee experiment and what took place in Guatemala," Besser said. "You had two populations that were mistreated for the benefit of medical knowledge."
Although it was common practice to use unwitting subjects for medical experiments in those days, then-Surgeon General Thomas Parran said about the Guatemala study, "You know, we couldn't do this in this country."
"It used to be that the idea of informed consent -- asking permission -- was unheard of," said Besser. "Sixty years ago, there weren't ethical boards, there weren't institutional review boards reviewing studies determining what you could and couldn't do. It's a different world today."