Bakground : Patient-Controlled Analgesia (PCA) has become popularized for postoperative pain control. Theoretically, addition of a basal infusion would ameliorate the pain control as related to less need for additional demands. Regardless of theoretical background, usefulness of a basal infusion in PCA is controversial. Therefore, in this study we compared the analgesic consumption between PCA only and PCA plus basal infusion and assessed if the use of a basal infusion improves the analgesic efficacy in intravenous PCA. METHODS: 40 patients undergoing caesarian section, were assigned randomly to PCA only group (group 1) and PCA plus basal infusion group (group 2). Group 1 was programmed to deliver 1.5 ml of bolus infusion with 10 minutes of lockout interval and four times per hour of the maximum usage of patient control module. In group 2, 0.5 ml of basal infusion was added to the same PCA. The analgesic solution contained 60 mg of morphine, 180 mg of ketorolac and 5 mg of droperidol in total volume of 60 ml. PCA was started at the time of the peritoneal closure with 2 ml of loading dose in all patients. Postoperative assessments were pain score, sedation score, side effect, total analgesic consumption and the degree of patients, satisfaction. RESULTS: Total analgesic consumption was significantly greater in group 2 than in group 1. Pain score, sedation score, complication and the degree of the satisfaction were almost the same at all time interval in each group. CONCLUSION: We concluded that there was no significant benefit of basal infusion in intravenous PCA after caesarean section.