Background: Post-operative nausea and vomiting (PONV) following surgical operations requiring general anesthesia are common and distressing. The incidence of PONV may be as high as 70% during the first 24 hrs of tonsillectomy. Objective: This study determines the effects of intraoperative well-hydration on postoperative nausea and vomiting. Methods: 90 ASA I patients with age of 6-12 years scheduled for tonsillectomy under general anesthesia randomly assigned to receive either routine iv fluid plus intraoperative well-hydration plus 4 ml/kg/h Ringer’s solution (well hydrated group; n=45) and routine iv fluid requirements (control group; n=45). All study preparations were administered in a double-blinded fashion. Results: During the first postoperative day, the incidence of nausea and vomiting were significantly lower in the well-hydrated group as compared with control (p<0.05). There was no significant differences between males and females regarding the incidence of nausea and vomiting (p>0.05). Conclusion: The present study showed that well-hydration reduces the incidence of post tonsillectomy nausea and vomiting, and high iv fluid therapy is a simple, effective, safe and well-tolerated technique for prevention of postoperative nausea and vomiting.