Objective: Due to its pharmacological properties, opipramol may be useful in the context of evening premedication in anaesthesiology. This trial examines whether quality of sleep the night prior to surgery can be improved by opipramol and whether this effect is dose dependent. A second objective of this study is to examine whether the emotional state (in particular anxiety) is affected by opipramol. Method: 72 female patients were randomly assigned to 100 mg opipramol, 150 mg opipramol or placebo (24 patients per group) in a double-blind trial. Drug application was in the evening prior to an elective surgery. Effects were recorded the next morning by means of self-rating questionnaires regarding subjective sleep quality of the last night and patients' current subjective state. The self-rating was done by use of the Wuerzburg Sleep Questionnaire, by use of mood inventories [BSKE (EWL) and STAI-X1] and by use of the Multidimensional Somatic Symptom List. Further dependent variables were heart rate and blood pressure. Confirmatory data analysis was conducted for subjective quality of sleep. Results: 100 mg opipramol as well as 150 mg opipramol significantly improved subjective quality of sleep (p < 0.001). The drug conditions did not differ in this effect. Opipramol marginally reduced anxiety (STAI-X1). The autonomic variables remained uninfluenced. There were no adverse events and no hints for interaction with anaesthesia. Conclusion: Opipramol may be used as a premedication in the evening prior to surgery if the primary target is an impact on the experienced quality of sleep. For this a single dosage of 100 mg opipramol is sufficient and can be recommended.