We have compared the effects of fentanyl and pethidine in the treatment of postanaesthetic shivering. Fifty patients who were shivering after routine abdominal surgery were allocated randomly to receive fentanyl 75 µg and pethidine 25 mg. After 10 min, 23 patients in pethidine group and 22 patients in the fentanyl group had stopped shivering which was not significantly different in the two grou...