This rare fatal disease of infants and early childhood occurred in seven children from four families. Six children died during 2-4 weeks from the beginning of disease, the last one has survived two years with cytostatic treatment. The disease was characterized by intermittent fever, hepatosplenomegaly and progressive pancytopenia as well as hyperbilirubinemia, hyperlipemia and hypofibrinogenemia. In addition to substantial enlargement of the liver and spleen prevailing autoptic findings were infectious complications due to severe immune defect or signs of hemorrhagic diathesis. Lymphocytes and histiocytes phagocytizing blood cells were increased in bone marrow, liver, spleen, often brain and further organs. Problems of differential diagnosis and pathogenesis were discussed.