One hundred twenty-seven successfully methadone-hydrochloride-maintained patients were randomly assigned to one of the following four groups and studied for 30 weeks: (1) known maintenance-patients were maintained on methadone under open conditions; (2) blind maintenance-patients were maintained on methadone under double blind conditions; (3) rapid withdrawal-patients were withdrawn under double-blind conditions at a rate of 10% of initial dose per week; (4) gradual withdrawal-patients were withdrawn under double-blind conditions at a rate of 3% of initial dose per week. Differences in dropout rates, illicit drug use, symptoms scores, and requests for study interruption indicate that withdrawal from methadone maintenance should be carried out at approximately 3% of initial dose per week. Better patient preparation also is indicated to reduce the effects of expectation.