The purpose of this study was to compare the effectiveness of three smoking cessation programs of varying intensity applied in a primary care setting. Participants were 89 individuals randomly assigned to one of three treatment groups: brief counseling plus information pamphlet, self-help program with telephone follow-up, and intensive behavioral treatment. At the 12-mo. follow-up, intensive behavioral treatment (42.8% abstinence) was more effective than the self-help program (27.5%), which was in turn more effective than counseling (12.9%). Continued abstinence was also higher in the intensive treatment group (37.9%) than in the self-help (17.2%) and the counseling groups (9.7%), although these differences only reached statistical significance in the first and third of these groups. Treatment adherence was higher in the intensive behavioral group (82.8% of participants attended all the sessions) than in the self-help group (61.8% completed the program). The results appear to confirm a dose-response effect in the treatment of smokers and indicate satisfactory acceptability of intensive behavioral programs applied in primary care.