The availability and use of a methadone/clonidine combination versus clonidine alone in opiate detoxification were studied. In Phase I of the study, a sequential combination of methadone followed by clonidine was utilized in those patients presenting with a primary diagnosis of opiate dependence. During the Phase II of the study, only clonidine was available. Medications were administered only if the history and clinical findings indicated impending or acute opiate withdrawal syndrome. Overall, there was no difference between the Phase I and Phase II groups when the number of opiate dependent admissions, patients completing detoxification, and the patients completing a follow-up rehabilitation program were compared. However, the patients in Phase I whose clinical symptomatology warranted the use of methadone were more likely to complete the detoxification program when compared to the patients in Phase II who received clonidine only. There was no difference between the two groups in completion of a follow-up rehabilitation. Detoxification with clonidine alone was more likely to be successful if the patient has had prior detoxification experience with methadone or if there was a secondary dependence of alcohol, sedative, or tranquilizer present coexisting with the primary opiate dependence diagnosis.