Many interventions has been studied in order to prevent hypotension after spinal anesthesia in cesarean section e.g., fluid loading: colloid vs crystalloid, medications: ephedrine, phenylephrine, and metaraminol, etc. The recent study showed ondansetron (the antiemetic drug) can be effectively used to prevent hypotension after spinal anesthesia in normal patients or parturients. The action of ondansetron is believed to inhibit Bezold-Jarish reflex.