The series comprises 109 healthy females aged 14-49 years (mean age 28 years) hospitalized for legal abortion or diagnostic curettage. The patients were premedicated with morphine-scopolamine 0.4-0.7 ml i.m. (morphine 20 mg/ml, scopolamine 0.6 mg/ml) and atropine 0.01 mg/kg i.v. Ketamine 1.5 mg/kg was administered i.v. and immediately thereafter 2 ml of a coded solution i.v. consisting either of diazepam 10 mg or its solvent only. Supplementary doses of ketamine 0.2-0.4 mg/kg were administered when needed. Diazepam reduced the incidence of unpleasant dreams and experiences to a significant degree (p less than 0.01) according to the postanaesthetic interviews of the patients. Nausea occurred in the diazepam group in 2 per cent and in the placebo group in 17 per cent (p less than 0.01). In respect to the differences in opinion presented in literature the authors consider the time of administration of diazepam at induction to be of decisive importance and find prophylactic prevention of dreams justified as it cannot be predicted which of the patients will have unpleasant or even terrifying dreams. Dreams and/or experiences or their memories must be prevented at the stage at which the effect of ketamine commences. The authors do not, however, recommend ketamine anaesthesia for young adults, even when supplemented with diazepam. On the other hand, the authors consider the positive observations made during the study to be applicable to all other ketamine anaesthesias.