A 64-year-old male was admitted in September 1989 with complaints of fever and muscular weakness in the extremities. A peripheral blood examination on admission revealed WBC 10,300/microliters (monocytes 32%), RBC 195 x 10(4)/microliters, Hb 7.9 g/dl, Plt 12.8 x 10(4)/microliters with trilineage dysplasia. Bone marrow biopsy was normoplastic marrow with 25.7% of monocytes including immature blasts. Cytochemical analysis of the monocytes showed positive for peroxidase and dual esterase staining. Chromosomal analysis of peripheral blood revealed 46, XY, -7, +der(1) t(1;7)(p11;p11). A diagnosis of chronic myelomonocytic leukemia was made. Hemostatic studies revealed cryofibrinogenemia, marked platelet aggregation on blood smear, hyperfibrinogenemia and a marked increase in maximal amplitude of thrombelastogram. Treatment with prednisolone and VP16, resulted in a reduction of peripheral monocytes and a disappearance of cryofibrinogen, marked platelet aggregation and a decrease in muscular weakness. Nine months after diagnosis he died of DIC, pneumonia, lung abscess and sepsis.