Objective: The aim of the present study was to evaluate the effects of ondansetron for prevention of postoperative shivering.
Patients and Methods: The study was carried out on 40 patient ASA I or II scheduled for lower abdominal surgery. They were categorized into two equal groups Group I (Group P): Patients were receiving intravenous pethidine in a dose of 0.5 mg/kg. Group II (Group O): Patients were received intravenous ondansetron in a dose of 4 mg. just before induction of spinal block.
Results: The studied groups showed no significant difference regarding demographic data, or postoperative shivering. However, postoperative nausea, vomiting and sedation were significantly increased in pethidine when compared to ondansetron group.
 Conclusion: Ondansetron is effective as Pethidine for prevention of postoperative shivering. However, side effects postoperative nausea & vomiting were significantly higher in pethidine group. Thus, ondansetron could be used as a safe and effective alternative for pethidine for postoperative shivering.