BACKGROUND: The alpha2-adrenergic agonist clonidine has been extensively studied as an adjunct to general and regional anesthesia. Clonidine has been added to local anesthetic regimens for various peripheral nerve blocks, resulting in prolonged anesthesia and analgesia. The purpose of this study was to evaluate the effectiveness of that using clonidine as a component of intravenous regional anesthesia (IVRA) to enhance postoperative analgesia. METHODS: Thirty-six patients undergoing hand surgery received IVRA with mepivacaine 0.5%, and were assigned randomly and blindly to one of the following groups as follows: Group I (n = 12) received only mepivacaine. Group II (n = 12) was given 0.5 microgram/kg clonidine as part of the IVRA solution. Group III (n = 12) received 1.0 microgram/kg clonidine as part of the IVRA solution. After the end of the operations, the analgesic effects were evaluated by using the visual analogous scale (0-10). Sedation scores (0-3), supplemental analgesic use, and side effects were also evaluated. RESULTS: The patients who received IVRA with 1.0 microgram/kg clonidine reported significantly lower pain score after tourniquet deflation compared with other groups, and a decreased need for analgesic in the postanesthesia care unit. No significant postoperative sedation, hypotension, or bradycardia developed in any of the patients. CONCLUSIONS: The addition of 1.0 microgram/kg clonidine to mepivacaine 0.5% for IVRA provided improved analgesia in the postanesthesia care unit after the operation and decreased the need for analgesic supplements after the operation.