In this double-blind, placebo-controlled trial, bupropion (BUPRO, 300 mg/day) was compared to placebo (PBO) for the concurrent treatment of opioid and tobacco addiction in 40 opioid-dependent smokers stabilized on buprenorphine (BUPRE, 24 mg/day). Participants received contingent, monetary reinforcement for abstinence from smoking, illicit opioids, and cocaine. Significant differences in treatment retention were observed (BUPRE+BUPRO, 58%; BUPRE+PBO, 90%). BUPRO treatment was not more effective than placebo for abstinence from tobacco, opioids, or cocaine in BUPRE-stabilized patients. These preliminary findings do not support the efficacy of BUPRO, in combination with BUPRE, for the concurrent treatment of opioid and tobacco addiction.