Background: The purpose of this study was to compare the relative analgesic officacies of the postoperative intra-bursal infusion of bupivacaine, bupivacaine/morphine, and bupivacaine/fentanyl after shoulder arthroscopy. Methods: At the end of subacromial arthroscopy, a continuous intra-bursal infusion catheter was inserted. A bolus dose was injected via the catheter just after the operation and a maintenance dose was infused for 4 days (1 ml/h). The bupivacaine group Group B, n " 2), received 10 ml of 0.5% bupivacaine and 96 ml of 0.25% bupivacaine. The bupivacaine/morphine group (Group BM, n " 25), received 2 mg of morphine in 10 ml of 0.5%bupivacaine and 8 mg of morphine in 96 ml of 0.25% bupivacaine. And the bupivacaine/fentanyl group (Group BF,n " 25) received 100 ng of fentany1 in 10 ml of 0.5% bupivacaine and 400 ㎍ of fentanyl in 96 ml of 0.25% bupivacaine, VAS at rest and exercise were evaluated preoperatively and postoperatively for 3 days. The frequency of IM rescue analgesic were recorded. Results: We did not find any significant differences in VAS, or in need for rescue analgesic between the three goups. Resting pain score was significantly reduced at the 2 nd-and postoperative day ersus the properative value in Group B and BM, and at the 3 rd postoperative day in Group BF (P < 0.05). Pain score at exercise was reduced at the 3 rd postoperative day versus the preoperative value in all groups (p < 0.05). Canclusions: The combination of morphine of fentanyl with bupivacaine did not provide better postoperative analgesia than bupivacaine after shoulder arthroscopy. (Korean J Anesthesiol 2004; 46: 323∼328)