Methadone medical maintenance is the treatment of stable methadone-maintained patients in primary care physicians' offices under an exemption from federal methadone regulations. Reports from seven such programs in six states show high retention and low frequencies of illicit drug use. Patients and physicians indicate high levels of satisfaction. Although methadone maintenance has a long history of safety and efficacy, most methadone medical maintenance programs are no longer operating or accepting new patients. Federal regulations for standard methadone clinics allow some features of methadone medical maintenance, and advocacy for state approval of these changes is strongly recommended.