Sixty patients who shivered after routine surgery under general anaesthesia were allocated randomly to receive normal saline (n = 20), doxapram 1.5 mg kg-1 (n = 20) or pethidine 0.33 mg kg-1 (n = 20). Both doxapram and pethidine were effective in treating postoperative shivering 2-3 min after i.v. administration. In the group who received normal saline, 15 patients were still shivering 10 min after treatment, whilst in the doxapram group only three patients were shivering at that time. In the pethidine group, all patients had stopped shivering by 7 min after treatment. We conclude that both doxapram and pethidine were effective in the treatment of postoperative shivering.