A blind comparison was made of butorphanol 2 mg with morphine 10 mg i.m. as the sole premedication in four groups, each of 10 women, undergoing total abdominal hysterectomy. On both subjective and objective grounds, butorphanol was as effective as morphine with the advantage of fewer unwanted side-effects, although one patient complained of hallucinations. No clinically significant antagonism could be demonstrated between butorphanol and fentanyl. One patient gave accurate recall of intraoperative events, which reflects the problem of designing a properly constructed scoring system, based on basic clinical signs, to predict accurately the adequacy of anaesthesia.