Abstract The goal of this study was to compare the effects of 1, 3 and 8 mg per day doses of buprenorphine in the maintenance treatment of opium-dependent subjects in Iran over a treatment period of 12 months. Participants were randomized to three equal groups (171 subjects per group) of opium-dependent individuals who met the DSM-IV criteria for opioid dependence and were seeking treatment. They were treated in an urban outpatient clinic, offering a 1-hour weekly individual counseling session. Overall, 282 subjects (55%) completed the 12 months study. Completion rates by dosage group were 46 (26.9%) for the 1 mg dose group, 102 (59.6%) for the 3 mg dose group, and 134 (78.4%) for the 8 mg dose group ( p = .000). These findings are consistent with previous reports of effective buprenorphine use in western countries as a suitable maintenance treatment for opium dependence.