The current study aimed to disseminate the logic of rational use of medicines and its application in medical practice among medical students at UNESC, Santa Catarina State, Brazil. The study's model was the training course on Rational Use of Medicines promoted by the World Health Organization (WHO), using the problem-based teaching-learning method, a strategy adopted by the UNESC School of Medicine in general. With support and funding from the Office of the Dean for Research and the Office of the Dean for Extension and Community Action (UNESC), the project was developed along two lines: first, training undergraduate medical students in the logic of Rational Use of Medicines; second, develop educational activities in the community, in neighborhoods near the university, on themes related to Rational Use of Medicines. Thirty-five students were trained, and community interventions were conducted with a total of 689 community members. The medical students involved in this project began to view prescriptions more rationally and gained a notion of the importance of prioritizing a list of essential drugs, for treatment supported by the best available evidence.