Enzyme replacement therapy (ERT) with exogenous glucocerebrosidase is indicated to treat symptomatic Gaucher disease (GD), a rare, inherited metabolic disorder. ERT with velaglucerase alfa, which is produced in a human cell line using gene activation technology, was studied in a 12-month phase III trial in Japanese patients with type 1 or 3 GD who were switched from imiglucerase ERT (n = 6); the current, open-label, 12-month extension study was designed to assess longer-term safety and efficacy. Two adult and three pediatric patients(aged b18 years) were enrolled into the extension study. Every-other-week intravenous infusions were administered for 63–78 weeks at average doses between 51.5 and 60.7 units/kg. Three non-serious adverse events were considered related to velaglucerase alfa treatment, but no patient discontinued from the study. Six serious but non-drug-related adverse events were reported. No patient tested positive for anti-velaglucerase alfa antibodies. Hemoglobin concentrations, platelet counts, and liver and spleen volumes (normalized to body weight) in these patients were generally stable over a cumulative 24-month period from the baseline of the parent trial. The data suggest that velaglucerase alfa was well tolerated and maintained clinical stability in Japanese GD patients over 2 years after switching from imiglucerase. ClinicalTrials.gov identifier NCT01842841.