Although susceptibility to infections in Kabuki make-up syndrome (KMS) has frequently been reported, there have been few immunological studies. We describe a 14 year old girl with KMS exhibiting chronic idiopathic thrombocytopenic purpura (chronic ITP), including immunological studies. Corticosteroid therapy was not effective therefore splenectomy was performed. The patient's platelet count increased transiently. Immunological studies revealed normal T cell functions and low serum immunoglobulin A (IgA) levels. Because of the abnormalities of B cell functions in chronic ITP and low serum IgA levels in our patient, we speculate that there may be some abnormalities of humoral immunity in KMS.