Objective: to evaluate the difference between perceived norms about drug use among peer and actual drug use as reported by the same university students. The students were between 18 and 24 years old and attended health courses. Method: cross-sectional study based on a survey, using an anonymous questionnaire filled out by the students. Results: There were 306 participants. Senior students used drugs as follows: 51.3% used tobacco, 90.8% used alcohol, 5.9% used marijuana, and 0.7% used cocaine. Differences were observed between perceived norms and actual drug use for tobacco (70% vs. 51.3%), marijuana (10% vs. 5.9%) and cocaine (8.3% vs. 0.7%). Conclusions: university students presented an overestimated rate for the use of tobacco, marijuana and cocaine among their peers.