We present a case of acute megakaryoblastic leukemia identified by electron microscopy and platelet-specific antibodies. The histological examination of bone marrow showed distinct myelofibrosis. In accordance with recent communications, low-dose cytosine arabinoside treatment (20 mg twice daily s.c. over 21 days) was initiated. The subsequent bone marrow examination showed a severe hypoplasia with persistent blasts. Amsacrine and VP-16 were given without success. Finally the patient died of septicemia without proof of pathogen uninfluenced by antibiotic and antiseptic therapy 6 weeks after diagnosis. Our case report confirms the poor prognosis of acute megakaryoblastic leukemia.