The aim of adequate preoperative medication is to minimize the patient's anxiety level. Preoperative anxiety can be consciously and specifically orientated or it can be masked. This double-blind study was performed to evaluate the effects of an anxiolytic drug in comparison with a placebo perioperatively and to assess the post-operative course of the important factors anxiety, depression and asthenia. The Mannheim inventory for subjective state and STAI (State-Trait-Anxiety-Inventory) were offered. The study was undertaken in 60 female patients, who were operated for suspected carcinoma of the breast. We conclude that in such a specific group of patients extensive preoperative psychological preparation must be backed up by the administration of an anxiolytic drug.