The cross-sectional study assesses lifetime use of psychoactive substances in medical students. During 2018, medical students from "Universidad de Buenos Aires" (UBA) in Argentina were offered the survey. Males significantly used at least one of the substances studied once in their lives compared to women (AOR: 1.75; IC 95%= 1.11-2.77). Similarly, males used more marijuana (AOR: 1.69; 95% CI = 1.08-2.63). The lifetime prevalence increased with career level for any substance, marijuana and stimulants. Being employed was associated with lifetime consumption of marijuana (AOR: 1.6; 95% CI = 1.03-2.48). Living with peers was associated with lifetime prevalence for stimulants (AOR: 3.5; 95% CI = 1.54-7.97). This study shows a lifetime prevalence for the total substances studied was higher compared to studies in the region. Marijuana was the substance with the highest consumption, with more than half surveyed having tried it.