Background and aims: A randomized, doubleblind, Phase III trial of velaglucerase alfa in type 1 Gaucher disease provides an opportunity to examine outcomes in pediatric patients.Methods: Of 25 patients in the trial, 7 pediatric patients (28%) were enrolled and randomized to receive velaglucerase alfa at 60 U/kg (n=4) or 45 U/ kg (n=3) as a 1-hour infusion, every other week for 12 months.Results: At 12 months, the mean hemoglobin concentration increased in both groups (60 U/kg: 16.3% increase, 1.74 g/dL, 95% CI: 0.72, 2.78; 45 U/kg: 24.7% increase, 2.77 g/dL, 95% CI: -0.99, 6.53). Mean platelet counts also increased in both groups (60 U/kg: 26.4% increase, +49.9×109/L, 95% CI: -32.1, +131.9; 45 U/kg: 38.9% increase, +60.3×109/L, 95% CI: -103.1, +223.7). Mean spleen volume, normalized by body weight, decreased in both groups (60 U/kg: 64.6% decrease, -2.1 cm3, 95% CI: -5.3, +1.1; 45 U/kg: 47.6% decrease, -0.7 cm3, 95% CI: -2.6, +1.2) as did mean liver volume (60 U/kg: 18.3%, -0.7 cm3, 95% CI: -1.4, 0.0; 45 U/ kg: 10.6% decrease, -0.3 cm3, 95% CI: -1.7, +1.1). No children developed antibodies to velaglucerase alfa, experienced a severe or a serious treatmentemergent adverse event, or discontinued due to an adverse event.Conclusions: In these pediatric patients with type 1 Gaucher disease, velaglucerase alfa was generally well tolerated at doses of 60 U/kg and 45 U/kg, and provided clinically meaningful improvements in disease parameters.Velaglucerase alfa is approved in the U.S.