The time to occurrence of cardiovascular complications after the beginning of an exercise rehabilitation program is variable. It is not clear whether such complications are related to the duration in the program. The aim of the present study was to assess the timing of cardiovascular events occurring during the activity and the long-term safety of a medically supervised cardiac rehabilitation program performed in the community, in a large cohort. We retrospectively evaluated 3,511 patients with a history of myocardial infarction, coronary artery bypass grafting and risk factors for coronary artery disease, participating in exercise training, for 69 months. The total number of patient-hours was 338,688 with an event rate of 1/58,902 patient-hours/year (0.02%). Non-fatal events occurred in 11 patients and fatal cardiovascular events in 2 patients; 1 was successfully resuscitated. Most of the non-fatal events (62%) occurred during the first 4 weeks from the beginning of the exercise program. One third of the patients who experienced cardiovascular events, resumed the exercise program with no further complications. Medically supervised cardiac rehabilitation program is accompanied by a very low incidence of cardiovascular events. Nevertheless, special caution should be undertaken during the first sessions of the program.