Sera from 23 individuals with Gaucher disease (GD) were analyzed for hypergammaglobulinemia and oligoclonal and monoclonal gammopathies. Serum IgG level was elevated in 15/23 (65%) patients, and a diffuse hypergammaglobulinemia was present in 10/23 (43%) patients. An oligoclonal gammopathy was noted in six patients, and a monoclonal gammopathy in two. Lymphocyte subset analysis was also carried out in eight individuals with GD. Four of five individuals showed increased surface Ig‐positive lymphocytes, while 7/7 were positive for either increased CD19‐ and/or CD20‐positive lymphocytes. An eighth patient was found to have a B‐cell leukemia. Statistical analysis of k and λ histograms were suggestive of a monoclonal excess. However, restriction enzyme analysis of four individuals with GD and increased B cells failed to show any evidence of Ig gene rearrangements. Serum Ig abnormalities and perhaps B‐cell lymphocytosis appear to be common in the GD patient population and are not associated with circulating monoclonal lymphocytes.