The authors present a conceptual model of the determinants of the counseling practices of physicians and an empirical test of the model. Seventy-six per cent of a 50% random sample of physicians in a western county medical society completed a questionnaire (n = 151). This instrument measures the aggressiveness, the indications and techniques used by physicians in counseling patients about smoking, exercise, weight control and alcohol use. The independent variables assessed by this instrument are motivations, perceived skills and barriers, medical specialty, and personal health habits. Significant associations were found between the counseling practices reported and physicians' personal health habits, attitudes and specialties. Non-surgeons counseled more patients, counseled more intensively, and used a greater variety of techniques than surgeons and obstetrician-gynecologists. In general, physicians who had poor health habits did not fully counsel patients about those habits; however, physicians attempting to improve poor habits counseled patients significantly more often than physicians who were not trying to change their own behavior. Health maintenance efforts among physicians may have a multiplier effect.