This is a report of Fechtner syndrome in two Japanese families. Six members of family I and three members of family II were studied. All but one had macrothrombocytopenia and leukocyte inclusion bodies, four had deafness, four had persistent proteinuria and none had cataracts. Under a diagnosis of ITP, two of them had splenectomy which resulted in no response. History revealed, other family members with deafness and/or nephritis were confirmed in both families. Ultrastructural studies of leukocytes showed oval inclusion bodies with unclear borders containing many fine ribosome like granules and randomly scattered filaments. Ultrastructural studies of macrothrombocytes were unremarkable except for a well-developed open canalicular system. More than half of megakaryocytes had uneven basophilic speckles in the cytoplasm, which were positive for Unna-Pappenheim staining. Ultrastructurally, widening of demarcating systems and remaining ribosomes were noted in the cytoplasma of mature megakaryocytes.