Serum immunoglobulin (IgG, IgA, IgM) levels have been determined in 22 splenectomized and 50 nonsplenectomized patients with β-thalassaemia major. Compared with 29 control subjects, all 3 immunoglobulins were statistically increased in the two thalassaemic groups. Splenectomized pa tients had higher levels of IgG and IgA, while IgM levels were found almost the same in both groups.