Pain, analgesic requirements, mouth opening and emesis were assessed in 60 patients who received either piroxicam 40 mg or placebo before dental surgery under general anaesthesia which included breathing either halothane or isoflurane. Patients went home on the day after surgery and completed a questionnaire concerning pain and emesis. There were four groups of 15 subjects: piroxicam-halothane, piroxicam-isoflurane, placebo-halothane or placebo-isoflurane. Pain increased at 2 and 4 h and had reduced by 18 h after surgery; there were no significant differences between the groups in pain scores. After operation, fewer patients in the piroxicam-isoflurane group required papaveretum compared with the piroxicam-halothane and placebo-halothane groups. Mouth opening was reduced between 2 and 4 h after surgery, but was less restricted after piroxicam-isoflurane than placebo-halothane. There was no difference between the groups in the incidence of emesis within 18 h of surgery. The postal questionnaire suggested that pain and emesis were reduced significantly during the 3 days after surgery in patients who had received piroxicam before surgery, compared with those who had received placebo.