Thirty-nine opioid-dependent outpatients were treated with the partial agonist buprenorphine at 2 to 6 mg/day for 1 month. Treatment retention was good (72%), and illicit opioid use decreased from 50% overall to 17% for those who remained in treatment. Precipitated withdrawal symptoms were mild and related to dose of buprenorphine. At the end of this month, 28 subjects were abruptly discontinued from buprenorphine and given the antagonist naltrexone. Withdrawal symptoms from buprenorphine were quite mild, and naltrexone was initiated in 20 patients (51% of total or 71% of those 28 completing 30 days on buprenorphine), but only 4 patients (10% overall) were successfully maintained on naltrexone for at least 2 weeks.