Background : Prostaglandin inhibitors have been successfully used to inhibit some types of postoperative pain and reduce opioids requirements in others. Antiprostaglandin activity may be ineffective unless the preparations are given at the appropriate time before surgery. This study aimed to determine if the intrarectal administration of acetaminophen immediately before surgery would markedly reduce pain in the postoperative period. Methods : The children were divided to two groups. Each group was consisted of 15 children. The children in control group were administered intramuscularly glycopyrrolate(0.004 mg/kg) 20 minute. The children in experimental group were administered glycopyrrolate(0.004 mg/kg) intramuscularly and were administered acetaminophen(250 mg) rectally 20 minute before the children were taken to the operating theatre. Results : In the recovery room, the children who had recived acetaminophen were signifcantlly quieter (p<0.01), agitated less(p<0.01) and cried less(p<0.01) painless(p<0.01) than those nonadministered group. There were no obvious differnces between the groups in intra-operative bleeding (as estimated by the surgeon), or in measured blood loss. No postopertive complications become evident. Conclusions : The preoperative rectal administration of acetaminophen for pain relief after tonsillectomy is safe and effective. (Korean J Anesthesiol 1997; 32: 27∼31)