In a randomized, double-blind study, we compared the prophylactic efficacy of ondansetron at a dose of 0.1 mg/kg (OND) vs. droperidol at a dose of 0.075 mg/kg (DBP) vs. placebo (PLA) in 120 patients undergoing pediatric 1-day ophthalmic surgery. Results showed an incidence of emesis in 10% of the OND group, in 37.5% of the DBP group and in 65% of the PLA group. Prophylactic administration of ondansetron represents the anti-emetic agent of choice in pediatric 1-day ophthalmic surgery.