AIM: To describe morbidity associated with gamma-butyrolactone (GBL) dependence, and outcomes of withdrawal. DESIGN: Case series. SETTING: Specialist out-patient clinic and affiliated in-patient detoxification unit. Patients with home support were offered the option of out-patient withdrawal management, based on high-dose diazepam and baclofen, titrated against withdrawal severity in an initial session lasting approximately 4 hours. Patients were then reviewed daily during the first 3 days of treatment, offered weekly follow-up for 4 weeks, and telephoned 2-4 months later. PARTICIPANTS: People dependent on GBL seeking detoxification. MEASUREMENTS: Drug history and social functioning were obtained by self-report in clinical interviews with a single clinician. Treatment completion, outcomes and adverse events associated with withdrawal are reported. FINDINGS: Patients reported impaired social functioning associated with GBL dependence and difficulty in accessing treatment. Nineteen patients commenced detoxification; 17 initially declined admission and were treated as out-patients. Mean diazepam dose in the first 24 hours was 75 mg (range 40-110 mg). Sixteen patients completed withdrawal, although several had lapses to GBL use during treatment. One patient developed delirium and required transfer to the in-patient detoxification unit. Most patients had persisting insomnia, anxiety and depression for weeks after withdrawal. CONCLUSIONS: GBL withdrawal can be managed in ambulatory settings, but needs to be backed up with seamless access to in-patient treatment if required.