A double-blind, parallel group study was carried out in 50 patients with an anxiety disorder to compare the anxiolytic efficacy and tolerability of a recently developed benzodiazepine, metaclazepam, with that of bromazepam. Patients were allocated at random to receive treatment for 2 weeks with either 15 mg metaclazepam or 4 mg bromazepam per day in two divided doses. Assessments were made using the Hamilton anxiety rating scale (physician) on entry and after 7 and 13-days' treatment, and a visual analogue scale (patients) on entry and at the end of the study. The results showed that there was a significant, marked reduction in anxiety rating scores after 1 and 2 weeks in both groups and a significant improvement in the patients' subjective assessment of their condition after treatment. Few side-effects were reported in either group.