BACKGROUND: This report updates 2001 estimates of disease burden prevented and cost effectiveness of tobacco-use screening and brief intervention relative to that of other clinical preventive services. It also addresses repeated counseling because the literature has focused on single episodes of treatment, while in reality that is neither desirable nor likely. METHODS: Literature searches led to four models for calculating the clinically preventable burden of deaths and morbidity from smoking as well as the cost effectiveness of providing the service annually over time. The same methods were used in similar calculations for other preventive services to facilitate comparison. RESULTS: Using methods consistent with existing literature for this service, an estimated 190,000 undiscounted quality-adjusted life years (QALYs) are saved at a cost of $1100 per QALY saved (discounted). These estimates exclude financial savings from smoking-attributable disease prevented and use the average 12-month quit rate in clinical practice for tobacco screening and brief cessation counseling with cessation medications (5.0%) and without (2.4%). Including the savings of prevented smoking-attributable disease and using the effectiveness of repeated interventions over the lifetime of smokers (23.1%), 2.47 million QALYs are saved at a cost savings of $500 per smoker who receives the service. CONCLUSIONS: This analysis makes repeated clinical tobacco-cessation counseling one of the three most important and cost-effective preventive services that can be provided in medical practice. Greater efforts are needed to achieve more of this potential value by increasing current low levels of performance.