A 62-year-old woman was admitted to our hospital because of general malaise in May, 1987. No hepatosplenomegary, skin eruption or lymphadenopathy was detected. Laboratory examinations showed mild anemia, thrombocytopenia, normal leukocyte count with no lymphocyte abnormality, hypogranular neutrophils, elevated serum lactic dehydrogenase, increased C-reactive protein and hypoxia. Bone marrow aspirate was normocellular with dysplastic changes in erythroid and megakaryocytic lines which agree with a diagnosis of myelodysplastic syndrome (MDS). She was treated with prednisolone which relieved her symptom but she developed high fever, hemiplegia and disturbance of consciousness and died in August, 1987. Necropsy of the kidney revealed large mononuclear cells within the lumen of small blood vessels. Immunohistochemical study of these malignant cells showed positive reaction to the anti-LCA and anti-L26 antibodies. And electron microscopy showed no azure granules in these cells. Then we diagnosed as neoplastic angioendotheliosis (NAE). To our knowledge, this is the first report of NAE with abnormalities in myeloid, erythroid and megakaryocytic lineages. These results suggest that NAE with MDS originate from a multipotent stem cell.