Background Patients' perceptions of their physician's role in smoking cessation, using the 4As protocol (asking, advising, assisting, and arranging), were assessed with a focus on associations with age (18-29, 30-49, and greater than or equal to 50) and stage of readiness to stop smoking (precontemplation, contemplation, and preparation). Methods. Self-administered questionnaires were completed by 524 smokers presenting for regularly scheduled appointments at six clinics of an HMO in the Chicago metropolitan area. Results. Almost all patients said their physician should ask about their smoking status and advise them to quit. About half said their physician should assist them with quitting, and about two-thirds said their physician should follow up (arrange) on their smoking behavior. Bivariate associations were found for endorsement of the 4As with both age and stage. Multiple logistic regressions found age was the most consistent and strongest correlate of 4As endorsement, with younger smokers more likely than those age 50 or older to endorse the 4As protocol. Conclusions. A proactive health promotion orientation should be encouraged among physicians. Patients should be screened for stage of readiness to stop smoking so that health care providers can emphasize aspects of the 4As protocol that are most appropriate for each patient. Age-tailored smoking cessation strategies should be employed within stages of readiness to stop smoking. (C) 1997 Academic Press.