Although adult alcohol use is negatively associated with tobacco cessation, this relationship has not been reported for adolescents. We assessed the relationship between alcohol use and point prevalence abstinence from smoking in a sample of tobacco-dependent adolescents undergoing cessation treatment. Alcohol use both at baseline and) during tobacco cessation treatment was examined as predicting smoking abstinence in 101 adolescents (age=15.1years, S.D.=1.31years; age at first cigarette=11.3years, S.D.=1.93years; age at first drink=12.01years, S.D.=2.87years) attending a total of 642 treatment visits. Mixed regression analysis showed that participants who reported alcohol use during tobacco cessation treatment were significantly less likely to abstain from tobacco smoking (OR=0.42, 95% CI=0.23-0.78, t=-2.78, df=540, p=0.0057). However, pre-enrollment alcohol use was not significantly associated with either short- or long-term tobacco abstinence. If confirmed in a larger group of adolescents, our findings suggest that youths attempting to quit smoking should abstain from alcohol.