This cross-sectional study compared perceived peer drug use and actual drug use in a sample of Latin American university students. Students from nine universities in five countries (Brazil, Chile, Colombia, Honduras and Peru) completed a questionnaire that addressed the use of tobacco, alcohol, marijuana and cocaine. Analysis focused on comparing perceptions to actual drug use. The findings largely, but not completely, confirmed the idea that students overestimate peer drug use. The unexpected findings were those relating to alcohol. While students generally overestimated peer use of tobacco, marijuana and cocaine, they accurately estimated or underestimated peer use of alcohol. Apart from the anomalous findings with regard to alcohol, this study shows that perceived drug use relates to actual drug use in Latin America as it does elsewhere. The results also support the suggestion that interventions using normative feedback would be useful to strengthen drug use prevention programs aimed at youth in Latin America.