Little is known about medical student beliefs about health promotion issues or about their prevention practices with patients. We administered a questionnaire about health promotion beliefs and practices to fourth-year medical students in a required course, "Preventive Medicine in Clinical Practice," at the University of Maryland School of Medicine. During a three-year period we surveyed 343 students. A majority of students believed that most of 23 health behaviors were of some importance to health promotion, and their responses were similar to those of practicing physicians in prior studies. Most students reported that they assessed preventive practices in their patients but did not feel well prepared to counsel patients about health issues. Students reported they were currently unsuccessful in modifying patient health behaviors and expressed limited optimism about future success in helping patients change health promotion behaviors with further training and support. There were no differences between students entering primary care specialties and other students. Information about medical student health promotion and disease prevention beliefs and practices can be applied in curriculum development.