A 3-year-old boy was transferred to our hospital because of fever, abdominal pain and severe systemic bone pain on October 16, 1989. Hematological examination showed hemoglobin 8.7 g/dl, white blood cell count 5300/microliters with 9% neutrophils and platelet count 5.5 x 10(4)/microliters. Bone marrow aspiration and biopsy revealed markedly necrotic cells. Blood chemistry showed transient elevation of CRP, serum LDH, FDP, FDP-Ddimer and fibrinogen. Tc99m pyrophosphate bone scanning showed multiple uptake spots in various bone. Although the sign of fever, abdominal pain and bone pain disappeared spontaneously after three weeks, anemia persisted. About two months later from bone marrow necrosis, abnormal cells appeared in the bone marrow. A diagnosis of AML (M3) was made and a combination chemotherapy started. This case is remarkable for elevation of acute phase protein in association with bone marrow necrosis.