Hyperimmunoglobulinemia is documented in patients with Gaucher disease of all ages. We investigated the frequency of hyper-immunoglobulinemia in 12 pediatric patients with type I and III Gaucher disease and the effects of enzyme replacement therapy on these abnormalities. The incidence of hyperimmunoglobulinemia was 77%, 66%, and 60% at the diagnosis, before and after ERT, respectively. Immunoglobulin G abnormalities were the most commonly seen isotype abnormality. After enzyme replacement therapy normalization of IgA and IgM levels were recorded but decline in IgG levels was less likely to occur. This study indicated the higher frequency of hyperimmunoglobulinemia in pediatric Gaucher patients. Pediatr Blood Cancer 2011;56:664-666. (C) 2010 Wiley-Liss, Inc.