Anxiolytic effects and tolerance of a four weeks treatment with prazepam (single dose of 40 mg in the evening) and with lorazepam (3 daily doses of 1.25 mg) are compared in a double blind study. Patients were treated by psychiatrists and were suffering from neurotic anxiety. Evaluation for therapeutic efficacy used a clinical global improvement scale and the Hamilton Anxiety Scale. Evaluation for side effects used the side effects symptoms check list. Anxiolytic effects of prazepam and lorazepam are not significantly different. Tolerance of the two treatments is comparable. The side effects are essentially an undesirable sedative action.