Acetaminophen and diclofenac are prescribed as postoperative analgesic agents in children. However, the efficacy of their combination is not studied sufficiently. We compare the analgesic effects of acetaminophen, diclofenac, and their combination after cleft palate surgery. In this randomized clinical trial, 120 children (1.5-5 y) who were scheduled for cleft palate repair were studied. Children were randomized to receive placebo, acetaminophen (40 mg/kg), diclofenac (1 mg/kg), or acetaminophen (40 mg/kg) plus diclofenac (1 mg/kg) rectally just after surgery. Acetaminophen (30 mg/kg) and diclofenac (1 mg/kg) were administered every 8 hours until 48 hours. Postoperative pain was assessed regularly with the Children Hospital of Eastern Ontario Pain Scale, and rescue analgesia was provided if scores were 7 or greater. Time to the first prescription of meperidine, total postoperative meperidine consumption, and adverse effects were the main outcomes.After surgery, pain scores were higher in placebo than in other groups in all time intervals. In the first 12 hours, pain scores in the combined group were less than those in the acetaminophen (P < 0.05) and diclofenac (P < 0.05) groups. Postoperative meperidine consumption was the highest in placebo and was the least in combined group (P < 0.05). It was significantly higher in the acetaminophen group than in the diclofenac group (P < 0.05). Time to the first prescription of meperidine was significantly different among all groups. Adverse effects were comparable among groups.Rectal acetaminophen plus diclofenac was found to be the most effective in pain control. However, both rectal acetaminophen and diclofenac were more effective than placebo, whereas diclofenac was more effective than acetaminophen.