One-hundred and eighty patients undergoing elective abdominal hysterectomy were anaesthetized in random order with isoflurane, enflurane or fentanyl in combination with nitrous oxide and oxygen. Incidence and severity of emetic sequelae (none, nausea, retching or vomiting) were studied during the first 24 h after the operation. Patients who received isoflurane had significantly (P less than 0.01) less emetic sequelae (27%) during the first 2 h in the recovery room compared with patients who received enflurane (45%) or fentanyl (48%). There was no difference between the groups in the overall incidence of emetic sequelae during the time period of 2-24 h post-operatively (isoflurane 65%, enflurane 77% and fentanyl 77%). Significantly (P less than 0.02) more patients had emetic sequelae if they had experienced nausea or had vomited after previous anaesthetics.