Detoxification was studied in well-rehabilitated, selected, methadone-maintained patients. Seventy-nine percent of 48 patients were successfully detoxified, functioned well, and were apparently drug-free when studied months after their last methadone treatment. Twenty-one percent returned to methadone maintenance treatment because of heroin use or the withdrawal syndrome. Other patients could not be detoxified, even in a slow, flexible dose-reduction regimen. It is recommended that the primary aim of methadone treatment is to facilitate rehabilitation. Decisions regarding detoxification should be made by the physician on an individual basis, after a year or more of successful treatment after weighing the degree of rehabilitation, relapse potential, and the patient's wishes.