BACKGROUND: The efficacy of epidurally administered tramadol hydrochloride, a weak centrally acting analgesic, was studied for the relief of postoperative pain. Clonidine, an alpha2 adrenergic agonist, has nonopiate antinociceptive properties which might be an alternative for postoperative analgesia free of undesirable effects from opioids. The aim of this study was to evaluate the postoperative analgesic effects of an epidural administration with a combination of tramadol and clonidine. METHODS: Sixty patients undergoing lower abdominal surgery were randomly allocated to three treatment groups to be given the following agents by the epidural route: group 1, 10 ml of bupivacaine 0.125%; group 2, 10 ml of bupivacaine 0.125% with tramadol 50 mg; group 3, 10 ml bupivacaine 0.125% with tramadol 50 mg and clonidine 100 microgram. In the recovery room, postoperative analgesia was assessed by the visual analogue scale (VAS) at 30 min, 1, 2, 3, 4, 5 and 6 hour. Vital signs, sedation score and side effects were also checked. RESULTS: VAS scores were significantly lower in group 3 than group 1. In addition, VAS scores were significantly lower in group 3 than group 2 at 4 and 5 hours. Blood pressure, heart rate and sedation scores were not significantly different among the three groups. CONCLUSIONS: The combination of epidural 0.125 % bupivacaine, tramadol 50 mg and clonidine 100 microgram produces more profound and longer postoperative analgesic effects than 0.125% bupivacaine and tramadol 50 mg or only 0.125% bupivacaine for the lower abdominal surgery.