Background: Maternal Spinal anesthesia frequently has side effects like hypotension and bradycardia during caesarean delivery. Maternal Spinal anesthesia frequently has side effects like hypotension and bradycardia during caesarean delivery. Objective: The current study aimed to evaluate effect of prophylactic intravenous ondansetron on hemodynamic parameters in elective cesarean section (CS) under spinal anesthesia. Patients and methods: A total of 80 patients with physical condition as defined by the ASA class II and ages ranging from 21 to 45 years old scheduled for surgery at Zagazig University's Department of Anesthesia and Surgical Intensive Care Hospitals; elective CS and Surgery were lasting no longer than 60 minutes. Patients in the control group (group C) got 10 ml of saline. Individuals in the ondansetron group (group O) received intravenously 4 mg of ondansetron diluted in 10 ml of saline five minutes before subarachnoid block. The following variables were measured throughout the course of the trial in both groups: systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MAO), heart rate, oxygen saturation percentage, and intraoperative need for ephedrine. Moreover, any issues that arise throughout or following operation were recorded.Results: The frequency of hypotension in expectant women undergoing spinal anesthesia for elective caesarean delivery was significantly reduced, when prophylactic 4 mg ondansetron was administered. The use of vasopressors Ondansetron significantly decreased the incidence of hypertension. Systolic blood pressure was consistently higher and fewer vasopressor medications were used in the ondansetron group. Conclusion: Intravenous premedication with 4mg ondansetron can effectively reduce the drop in SBP, DBP, and MAP in expectant mothers scheduled for CS.