To determine personal and clinical exercise-related attitudes and behaviors of freshmen U.S. medical students, we surveyed 1,906 entering freshman medical students (response rate=87%; average age=24 years) in 17 U.S. medical schools. Students reported a median of 45 min/day of exercise, 80 min/week each of mild and moderate exercise, and 100 min/week of strenuous exercise. Nearly all students (97.6%) engaged in some moderate or vigorous exercise in a typical week. Sixty-four percent complied with U.S. Department of Health and Human Services exercise recommendations. Most freshmen (79%) believed it would be highly relevant to their future practices to counsel patients about exercise; predictors included intention to provide primary care, excellent health, prevention emphasis by their personal physician, and performing more strenuous exercise.