Objective: To analyze the predictors of smoking cessation treatment outcomes in a sample with a high rate of medical and psychiatric disorders and addictions. Methods: Analysis of predictors of success of a 6-week treatment provided by an addiction care unit (CAPS-AD) to 367 smokers in Brazil from 2007 to 2010. Forty variables were collected at baseline. Success was defined as abstinence from smoking for a period of at least 14 consecutive days, including the last day of treatment. Twenty variables were selected for the logistic regression model. Results: The only condition correlated with successful treatment after logistic regression was smoking one's first cigarette 5 minutes or more after waking (beta = 1.85, 95% confidence interval [95%CI] = 1.11-3.10, p = 0.018). Subjects with hypertension and alcohol use disorders and those who were undergoing psychiatric treatment showed success rates comparable to or greater than the average success rate of the sample (34.2-44.4%). Conclusions: These findings support the importance of the variable time to first cigarette in treatment outcomes for a sample with a high rate of clinical and psychiatric disorders. Good success rates were observed for pharmacological treatment, which was combined with group therapy based on cognitivebehavioral concepts and integrated into ongoing treatment of other addictions and psychiatric disorders.