OBJECTIVE Parasacral sciatic nerve block has been shown to be easy to perform, but studies reported to date involve a total of only 155 patients. The aim of this study was to assess the efficacy of parasacral sciatic nerve block in a larger group of patients. METHODS Four hundred consecutive parasacral blocks were evaluated prospectively. The level of expertise of the practitioner, the time to perform the block, the lowest current intensity of nerve stimulation, the injected volume, the onset time, the success or failure of the block, and complications were recorded. RESULTS The time required to perform the block was 7 +/- 5 minutes. The lowest stimulation-current intensity was 0.4 +/- 0.1 mA, and the injected volume was 27 +/- 4 mL. The onset time was 13 +/- 7 minutes for both motor and sensory block in all nerve distributions. The success rate was 94% (376 of 400 cases). Nine supplemental injections were performed successfully, thus increasing the success rate to 96%. General anesthesia or heavy sedation was performed in 15 cases (3.8%). There was no difference in failure rate between more experienced and less experienced anesthesiologists. CONCLUSIONS In this prospective 400-case study, we confirmed previous findings that the parasacral approach is effective, easy to perform, and easy to teach, even when performed by relatively inexperienced physicians. The parasacral approach is, therefore, an effective alternative to other approaches of sciatic nerve blockade.