Background: The present study was designed to test the short-term efficacy and safety of naltrexone in the treatment of kleptomania. Method: 10 subjects (7 women, 3 men) who fulfilled DSM-IV criteria for kleptomania and were free from other Axis I diagnoses by the Structured Clinical Interview for DSM-IV screening participated in a 12-week naltrexone open-label trial. Kleptomania symptom change was assessed with the Clinical Global Impressions scale (both severity and improvement measures), Sheehan Disability Scale (SDS), Global Assessment of Functioning (GAF), and Kleptomania Symptom Assessment Scale. Side effects were monitored weekly, and liver function tests were administered every 2 weeks. Results: Naltrexone reduced urges to steal and stealing behavior. Subjects showed significant improvement (p < .005) over the 11-week treatment period in all measures compared with measures taken at baseline. Seven subjects (70.0%) were very much improved and 2 (20.0%) were much improved at study end. Subjects also reported overall significant improvement in social and occupational functioning as determined by both the GAF and the SDS (p < .000). Men responded to naltrexone as well as women. The mean naltrexone dose required for effective symptom control was 145 mg/day. Nausea was common during the first week of treatment. Five subjects (50.0%) reported previous trials of medication and cognitive-behavioral therapy without any effect on kleptomania symptoms. Conclusion: The present findings provide evidence that naltrexone may be effective in the treatment of kleptomania. The present report is preliminary. Further studies are needed to confirm these findings.