A double-blind, random design, parallel group, four-week study of prazepam, diazepam, lorazepam, and placebo was conducted in diverse private outpatient practices (surgeon, internist, and obstetrician-gynecologist) using a common protocol, in order to evaluate their comparative efficacy in these settings. In addition, the effects of these anxiolytics on depressive symptoms in patients with anxiety were studied. Results showed that the non-psychiatric practitioners used lower dosages than psychiatrists in previous reports, and perception of anxiety levels of their patients were lower than the psychiatric raters. When patients were divided into two groups (1. predominantly depressed with anxiety, and 2. predominantly anxious with depression), differences between the benzodiazepines were shown. In the high depression-low anxiety group, all four treatment methods were effective in alleviating both anxiety and depression. In the high anxiety-low depression group, only prazepam and placebo were effective in alleviating both anxiety and depression, while diazepam and lorazepam decreased anxiety levels, but not depression.