BACKGROUND: The purpose of this study was to determine whether the injection rate affects the spread of spinal anesthesia in cesarean sections. METHODS: Spinal anesthesia was performed on 45 parturients in a cesaren section. Dural puncture was performed in the sitting position with a 27-gauge Whitacre needle. All patients received a mixture of 10 mg hyperbaric bupivacaine and 15 microgram fentanyl. Twenty five (Group I) patients received rapid injections (about 0.2-0.3 ml/sec) and twenty (Group II) received slow injections (about 0.1 ml/sec). Anesthetic levels, time to T4 sensory block, maximal height sensory block and incidence of hypotension were measured. RESULTS: There was significantly rapid T4 sensory block in group I but no differences in maximal height of sensory block and incidence of hypotension between the two groups. CONCLSIONS: We conclude that injection rate (about 0.1-0.3 ml/sec) has a statistically insignificant influence on the maximal height sensory block and incidence of hypotension.