BACKGROUND: Intraarticular bupivacaine, clonidine and morphine produce good postoperative analgesia. This study was designed to compare the analgesic effects of intraarticular clonidine and morphine, used separately and in combination. METHODS: We studied 60 patients undergoing arthroscopic anterior cruciate ligament reconstruction of knee under spinal anesthesia using hyperbaric bupivacaine. Each patients received 30 ml of intraarticular 0.25% bupivacaine containing clonidine 150 g or morphine 2 mg or both. RESULTS: There were no differences in VAS scores at 0, 1, 2, 6, 12, 24, 36, 48 hr after operation and the dosage of postoperative analgesics among the groups. CONCLUSIONS: We concluded that 30 ml of 0.25% bupivacaine containing morphine 2 mg or clonidine 150 g provided comparable analgesia after intraarticular administration, but the combination of these drugs did not seem to increase analgesia.