Three hundred and sixty-six patients volunteered for a smoking cessation trial and were randomly allocated to a control group or to three interventions: a single counselling visit to a physician, eight sessions of group health education or eight sessions of group behavior modification. Progress was assessed by smoking diaries, supported by saliva thiocyanate tests, before and after the intervention and six and 12 months later. Only the two group approaches showed a significant improvement compared to the control group immediately after the intervention; these differences were no longer statistically significant six or 12 months later. The group methods proved to be more cost-effective than the physician intervention. However, when different sub-groups were examined, such as heavy or light smokers, a different pattern of results emerged. For very heavy smokers, the physician-led intervention proved almost as successful as the group approaches. Overall quitting results were disappointing, but the programs appear to be more successful at helping people reduce smoking.