BACKGROUND: Diclofenac is a nonsteroidal anti-inflammatory drug widely used as adjuvant for postoperative pain management using intravenous Patient Controlled Analgesia (PCA). The analgesic and hemostatic effects of diclofenac were measured in 80 paturients after Cesarean section. METHODS: Eighty parturients were randomly allocated to four groups and each group had 20 women. The parturients were given loading dose of meperidine in D group and morphine in M group and then postoperative pain was controlled with PCA device for up to 48 hours after Cesarean section when the parturients awoke and complained pain. The parturients received intramuscular diclofenac 75 mg followed by loading dose of meperidine in DV group and morphine in MV group. Diclofenac was repeated every 12 hours. We evaluated the effects of diclofenac on postoperative opioid requirement, numerical rating score of pain and hemostasis at 48 hours after operation. RESULT: Diclofenac decreased almost 50% of opioid requirement and pain score lowered significantly at 12, 24 hours in DV group and at 12 hours in MV group. But there was no difference in laboratory data including hemoglobin, hematocrit, platelet count and bleeding time among the groups. CONCLUSION: We concluded that diclofenac is effective and safe adjuvant for postoperative pain management without hemostatic abnormality. But it is necessary to try further evaluation of hemostatic effect of diclofenac.