Alfentanil, a new narcotic analgesic with a rapid onset and short duration of action was used as an adjunct to thiopentone and nitrous oxide anaesthesia in 109 patients undergoing dilatation and curettage (D&C) or therapeutic abortion (TA). The mean alfentanil dose was 19.7 +/- 9.6 microgram X kg-1 (D&C Group) and 23.3 +/- 6.6 micrograms X kg-1 (TA Group), with a mean duration of anaesthesia of about 30 minutes. The anaesthetic effect was judged excellent in virtually all patients (94.7 per cent in the TA group and 96.7 per cent in the D&C group). There were no significant changes in haemodynamic parameters intraoperatively. Apnea or hypoventilation was observed in four patients and was easily reversed by naloxone. Most patients (95.4 per cent) demonstrated complete recovery of consciousness, motor activity, respiratory and circulatory function and skin colour within 60 minutes of arrival in recovery room. The only consistent side effect was minor chest wall rigidity which was eliminated by pretreatment with d-tubocurarine. One patient experienced a serious adverse reaction which was reversed with naloxone. We have found alfentanil to be well suited as an adjunct to nitrous oxide and thiopentone in short surgical procedures.