To describe medical students physical activity in the Cayetano Heredia Peruvian University.

Cross-sectional study. We evaluated 315 medical students from April to May 2009, using a previously validated survey to obtain information about the personal habits, general concepts, environment and difficulties of the physical activity.

A total of 44.8% of medical students practiced aerobic physical activity and 31.4% physical strength activity. None of them knew how to define physical activity. Most of them, 83.3%, practiced more physical activity before entering University, and 93.3% said that their University did not promote physical activity.

The lack of time, knowledge and motivation were the difficulties for practicing any type of physical activity, although more than half of the medical students did so. The most important factors associated were the interruption of the healthy life habits due to study load, the lack of knowledge about physical activity and education in undergraduate medical programs.