Sixty-six physicians were randomized to three groups to conduct a 1-month campaign to help their patients stop smoking. The workshop group received free patient education materials and a 6-hour training workshop. The materials group received free patient education materials, and the no-assistance group received nothing. A telephone interview was completed with 89% of the 6767 eligible adult patients seen during the month of the campaign. The brief training program and patient education materials marginally increased the smoking intervention activities of volunteer physicians in private practice. Both workshop and materials physicians asked 54% of their smoking patients to stop; no-assistance physicians asked 40%. One year later, 36% of patients who had not even been asked by their doctors if they smoked reported that they had tried to stop smoking. If the physician had asked the patient if he or she smoked, the probability of a quit attempt was 47%. Patients who had been asked if they smoked were more likely to claim to have stopped (13%) than patients who had not been asked (9%). However, the proportion of patients claiming continued abstinence (range, 12% to 14%) was not related to the group of the physician.