Although there is a strong relationship between depression and smoking, most nicotine dependence treatment trials exclude depressed smokers. Our objective was to determine whether bupropion improves abstinence rates and abstinence-associated depressive symptoms when added to transdermal nicotine replacement therapy (NRT) and group cognitive behavioral therapy (CBT) in smokers with unipolar depressive disorder (UDD). Adult smokers with current (n = 90) or past (n = 109) UDD were randomly assigned to receive bupropion or placebo added to NRT and CBT for 13 weeks. In the primary analysis, with dropouts considered smokers, 36% (35/97) of those on bupropion and 31% (32/102) on placebo attained biochemically validated 7-day point prevalence abstinence at end of treatment (not significant). Because of a high dropout rate (50%) and a significant difference in abstinence status at dropout by treatment group, a traditional intent-to-treat analysis with last observation carried forward imputation of abstinence status was performed. In this secondary analysis, 56% (54/97) of those on bupropion and 41% (42/102) on placebo met criteria for abstinence at end of trial, χ2 = 4.18, P = 0.04. Nicotine replacement therapy usage and absence of a comorbid anxiety disorder predicted abstinence. Abstinence was associated with increased depressive symptoms, regardless of bupropion treatment. Thus, in the primary analysis, bupropion neither increased the efficacy of intensive group CBT and NRT for smoking cessation in smokers with UDD nor prevented abstinence-associated depressive symptoms. Bupropion seemed to provide an advantage for smoking cessation for those who remained in the trial. The dropout rate was high and was characterized by a higher prevalence of current comorbid anxiety disorder. Given the high abstinence rate achieved with CBT plus NRT, a ceiling effect related to the high level of intervention received by all subjects may have prevented an adequate test of bupropion.