BACKGORUND: The admixture of clonidine or fentanyl to 1.5% lidocaine for brachial plexus block was studied with regard to onset and duration of anesthesia and postoperative analgesia after a brachial plexus blockade. METHODS: Thirty patients (ASA i-ii) undergoing surgery of the forearm and hand under an interscalene brachial plexus blockade (BPB) were included in this study. Patients were randomly divided into 3 groups. BPB was performed using 40 ml of 1.5% lidocaine added epinephrine 1:200,000 in group E, 1mug/kg of fentanyl in group F, and 2mug/kg of clonidine in group C, respectively. The onset times of blockade in the radial, ulnar, median and musculocutaneous nerve were recorded. Hemodynamic data and sedation scores were monitored. Finally, the duration of the sensory block was assessed. A value of P<0.05 was considered as statistically significant. RESULTS: The clonidine group was shorter in onset time, decreased need for postoperative analgesia and increased analgesic duration than other groups but more sedated than group E. With the admixture of fentanyl, pain scores were lower at 180 and 210 min after the block (VAS:mean 2, 8) than with epinephrine (VAS:mean 27, 30 respectively). Hemodynamic changes were not significantly different in all groups. CONCLUSiONS: The addition of clonidine to 1.5% lidocaine causes a rapid onset of analgesia and prolonged duration of sensory blockade in the brachial plexus blockade when compared to the addition of epinephrine or fentanyl to 1.5% lidocaine.