Objectives, The present study used telephone support both to sustain abstinence and to encourage renewed - quit attemps in smokers who had completed an intensive smoking cessation clinic. Methods. Subjects weres hardcore smokers (n = 1083) who had attended a multisession cessation clinic. They were then assigned randomly to receive telephone support (intervention calls 3, 9, and 21 months after - the targeted cessation clinic quit date) or no further intervention. Results. In the interventíon condition, subjects who relapsed were significantly more likely to resume abstinence (that is, to 10 recycle) than those in the comparison condition at follow-up (6 months: 17.8% vs 11.3%: 24-months: 25.7% vs 18.2%). Telephone support was not effective in preventing relapse, and overall differences in abstinence outcome were not significant. Conclusions, The major hypothesis of the current study - that tetephone support would enhance the resumption of abstinence - received partial support. However, there was no evidence either or an overall treatment effect or of an effect in preventing relapse. Telephone out-reach may be more effective in the context of be self-help or other less intensive interventions.