In this double-blind, randomized, placebo-controlled study, we evaluated the efficacy and safety of different doses of prophylactic IV dexamethasone for postoperative nausea and vomiting (PONV) in 168 children (aged 2-15 yr) scheduled for strabismus surgery. Patients received IV dexamethasone 0.25 mg/kg (D 0.25), 0.5 mg/kg (D 0.5), 1.0 mg/kg (D 1), or saline (S) immediately after induction of general anesthesia. Patients were discharged 24 h after surgery. Nausea and vomiting were assessed at 0-2, 2-6, and 6-24 h after surgery. Blood glucose was measured preoperatively and at 4 h after study drug administration. Wound healing and infection were assessed after 1 wk. More patients in group S had vomiting at 0-2, 2-6, and 6-24 h (P = 0.001, P = 0.003, and P = 0.04, respectively) and required larger doses of rescue antiemetics compared with the dexamethasone groups. Fewer patients in the dexamethasone groups (6, 3, and 6 in D 0.25, D 0.5, and D 1, respectively) had severe PONV compared with group S (P = 0.001). No significant increase in postoperative blood glucose levels was observed and wound healing was satisfactory in all four groups. The results suggest that dexamethasone 0.25 mg/kg is more effective than saline and equally effective compared with larger doses for preventing PONV for pediatric strabismus surgery.