The use of conventional dose of bupivacaine for transurethral surgery is associated with a high incidence of hypotension, prolonged motor recovery and discharge time. It may be possible to minimize these unwanted outcome by using either smaller dose of bupivaciane or minidose of bupivacaine combined with fentanyl. Eighth six patients undergoing transurethral surgery were randomized into two groups receiving spinal anesthesia with hyperbaric bupivacaine 5 mg plus fentanyl 10 mcg (group I) and hyperbaric bupivacaine 7.5 mg (group II). We evaluated the adequacy of anesthesia and their effects on the incidence of hypotension, sensory level, motor blockade, discharge time, and surgical condition. The median of the upper limit of the sensory block at the ten minutes testing time in both groups was T6 equally. Motor blockade was significantly more intense in group II (p=.008). The incidence of hypotension was minimal, four patients (9.5%) in group I and two patients (4.5%) in group II were treated with only single dose of 0.25 mg metaraminol. Surgical condition was rated as good 97.6% (41/42) in group I and 100% in group II. PACU time was not different significantly, 30.8 ± 2.5 minutes in group I and 32.3 ± 6.9 minutes in group II (P = 0.203). Patients' satisfaction were rated as good 97.6% (41/42) in group I and 97.7% (43/44) in group II. We concluded that the minidose of hyperbaric bupivacaine 5 mg in combination with fentanyl 10 mcg intrathecally provided adequate surgical anesthesia in transurethral surgery, with less intense motor blockade and minimal incidence of hyptension.