Student leagues have been created by medical students all across Brazil. Accepted as extracur ricular university extension activities, the leagues have produced both benefits and risks for medical training. Student leagues thus need to be rationalized, with the aim of improving their activities. This report describes the regulation adopted by the Botucatu School of Medicine (Universidade Estadual Paulista, FMB/UNESP), framed within a discussion of the importance of such leagues as extracurricular activities and the potential harm they can cause to medical training. The regulation contains procedural guidelines and a set of criteria for the evaluation of proposals to create new leagues. The criteria assess the proposal's relevance, objectives, planned management model, and training ideology. The use of these guidelines has allowed the development of projects for new leagues and triggered more in-depth reflection in the school on the role of student leagues.