BACKGROUND: Both ketorolac and propacetamol are used postoperatively to control mild to moderate pain. This study compared the analgesic efficacy of ketorolac and propacetamol delivered either preoperatively or postoperatively, and assessed the preemptive analgesic effect of ketorolac and propacetamol for adenotonsillectomy. METHODS: One hundred and two pediatric patients were divided randomly into four groups. The K1 and P1 groups received ketorolac 1 mg/kg or propacetamol 30 mg/kg after induction, respectively, whereas the K2 and P2 groups received each drug at the end of the operation, respectively. After adenotonsillectomy, we measured the NRS (Numerical Rating Scale), FPS (Faces Pain Scale) and OPS (Objective Pain scale) at 15, 30 and 60 min after arriving at the postanesthesia care unit. RESULTS: There were no significant differences in the NRS, FPS and OPS between K1 and K2 and between P1 and P2 for 60 min after operation at the postanesthesia care unit. CONCLUSIONS: These results suggest that both ketorolac (1 mg/kg) and propacetamol (30 mg/kg) have no preemptive analgesic effects during 1 hour after adenotonsillectomy.