A double blind study has been carried out on 60 women undergoing gynaecological surgery: they were divided into 2 groups who were given as premedication either midazolam: 10 mg, or diazepam: 15 mg intramuscularly. No significant differences between both groups concerning heart rate, blood pressure and respiratory rate were found. After 30 min sedation of anxiety was noted in 30 subjects (100%) after midazolam and in 20 subjects (67%) after diazepam (P less than 0.001). After 45 min good sedation was found in 19 patients (63%) after midazolam and in 4 patients (13%) afer diazepam (P less than 0.001). Amnesia related to preoperative period was more frequent in the midazolam group than in the diazepam group: 67% VS 13% (P less than 0.001). Amnesia of the immediate postoperative period was 100% in both groups. Midazolam as compared with diazepam can be regarded as a superior intramuscular premedicant. This superiority can been explained by a rapid and good resorption.