This study was done to compare the anesthetic efficacy and safety of three local anesthetic agents : racemic bupivacaine and its two isomers : ropivacaine and levobupivacaine, in patients undergoing transurethral resection of prostate. One hundred–sixty two patients, ASA I–III, were randomized to receive an intrathecal injection of one of three local anesthetic solutions. Group B (n = 54) received 2 ml of isobaric bupivacaine 5 mg/ml(10 mg). Group R (n = 54) received 2 ml of isobaric ropivacaine 5 mg/ml (10 mg). Group L (n = 54) received 2 ml of isobaric levobupivacaine 5 mg/ml (10 mg). The onset and duration of sensory block at dermatome level T10,time to achieve highest level of sensory block, regression of sensory block up to L–1 as well as the onset, and duration of motor block were recorded, as were any adverse effects, such as bradycardia , hypotension, hypoxia, tremor, nausea and/or vomiting.The onset of motor block was significantly faster in the bupivacaine group compared with that in the ropivacaine group and almost the same of that in the levobupivacaine group (P < 0.05). Ropivacaine presented a shorter duration of both motor and sensory block than bupivacaine and levobupivacaine (P < 0.05). Bupivacaine required more often the use of a vasoactive drug (ephedrine) compared to both ropivacaine and levobupivacaine and of a sympathomimetic drug (atropine) compared to the ropivacaine group.