Nineteen heroin-dependent male volunteers were administered buprenorphine sublingually, in ascending daily doses of 2, 4, and 8 mg. They were maintained on 8 mg daily through study day 18. On study days 19 through 36, subjects in group 1 continued to receive burprenorphine daily; subjects in group 2 received buprenorphine or placebo on alternate days. On days 37 through 52, all subjects received placebo. Subjects receiving buprenorphine on alternate days reported significantly greater urge for an opioid, increased dysphoria scores, and pupillary dilation on placebo days. After abrupt termination of buprenorphine, no withdrawal signs were detected with the Himmelsbach scale. However, subjects reported mild-to-moderate opioid withdrawal symptoms, peaking at 3 to 5 and lasting for 8 to 10 days. Daily administration of buprenorphine provided greater control of subtle opioid withdrawal symptoms, but subjects could tolerate a between-dose interval of 48 hours.