Aims To evaluate relapse prevention (relapse prevention) and contingency management (contingency management) for optimizing smoking cessation outcomes using nicotine replacement therapy for methadone-maintained tobacco smokers. Design Experimental, 2 (relapse prevention) x 2 (contingency management) repeated measures design using a platform of nicotine replacement therapy featuring a 2-week baseline period, followed by randomization to 12 weeks of treatment, and 6- and 12-month follow-up visits. Setting Three narcotic treatment centers in Los Angeles. Participants One hundred and seventy-five participants who met all inclusion and no exclusion criteria. Intervention Participants received 12 weeks of nicotine replacement therapy and assignment to one of four conditions: patch-only, relapse prevention + patch, contingency management + patch and relapse prevention + contingency management + patch. Measurements Thrice weekly samples of breath (analyzed for carbon monoxide) and urine (analyzed for metabolites of opiates and cocaine) and weekly self-reported numbers of cigarettes smoked. Findings Participants (73.1'%) completed 12 weeks of treatment. During treatment, those assigned to receive contingency management showed statistically higher rates of smoking abstinence than those not assigned to receive contingencies (F-3.4680 = 6.3, P = 0.0003), with no similar effect observed for relapse prevention. At follow-up evaluations. there were no significant differences between conditions. Participants provided more opiate and cocaine-free urines during weeks when they met criteria for smoking abstinence than during weeks when they did not meet these criteria (F-1.2054 = 14.38, P = 0.0002; F-1,F-2419 = 16.52, P < 0.0001). Conclusions Contingency management optimized outcomes using nicotine replacement therapy for reducing cigarette smoking during treatment for opiate dependence, although long-term effects are not generally maintained. Findings document strong associations between reductions in cigarette smoking and reductions in illicit substance use during treatment.