Data were collected on 50 patients with panic attacks who were treated with clonazepam to determine the drug's antipanic efficacy. At a mean duration of 54.3 weeks, 62% of the patients remained in treatment and 38% were lost to follow-up. Of those remaining in treatment, 90% had a good response to clonazepam and 10% a poor response. The author concludes that clonazepam demonstrated antipanic efficacy, that the development of tolerance or abuse was not a problem, and that most of the patients are being effectively maintained at 2-3 mg/day of clonazepam.