Hypotension is the most common adverse effect of spinal anesthesia for cesarean section. A number of strategies for preventing hypotension have been investigated. However, no method has proved entirely satisfactory. In a recent study, the use of small dose hyperbaric bupivacaine in well-hydrated patients is associated with a low incidence of hypotension. We randomized 80 parturients to a control trial to receive spinal anesthesia with either hyperbaric bupivacaine 7.5 mg (group I) or 10 mg (group II) with morphine 0.2 mg in both groups. We evaluated the adequacy of anesthesia and their effects on the incidence of hypotension, sensory level, motor blockade and surgical condition. The median of the upper limit of the sensory block at ten minutes testing time in both group was T4 equally. The incidence of hypotension in group I was 32.5% and in group II was 90%. Motor blockade was more intense in group II. One patient (2.5%) in each group was supplement with small dose of ketamine. Total ephedrine requirement in group I was significantly lower than group II (P<0.001). Surgical conditions were good in both groups. Patient's satisfaction was rated as good 92.5% in group I and 80% in group II. We concluded that hyperbaric bupivacaine 7.5 mg in combination with morphine 0.2 mg intrathecally provided adequate surgical anesthesia in cesarean section, with lower incidence of hypotension and vasopressor requirement.