The incidence and clinical manifestations of disseminated intravascular coagulation (DIC) were examined in patients with a range of underlying disorders. Out of 1,882 patients suspected as having DIC, 204 cases were diagnosed as suffering from DIC and included in this study. The underlying disorders experienced by the patients were solid tumors (33.8%), hematologic malignancies (12.7%), aortic aneurysm (10.8%), infections (6.4%), post-operative complications (4.4%), liver disease (2.9%), obstetric disorders (2.5%), and miscellaneous diseases (26.5%). The incidence of DIC was 10.8% out of all patients suspected of having DIC, and the etiologies were 10.9% in solid tumors, 10.1% in hematological malignancies, 20.4% in aortic aneurysm, 12.7% in infections, 15.5% in post-operative complications, 15.8% in liver disease, 3.7% in obstetric disorders, and 9.8% in miscellaneous diseases. The clinical manifestations of DIC patients were varying dependent on their etiologies. Most DIC patients with aortic aneurysm (95.5%) and post-operative complications (88.9%) did not reveal any clinical manifestations. Although all of the patients with obstetric disorders had bleeding, only 20.0% of the patients had organ failure. In contrast, although only 15.4% of the patients with infections had bleeding, 76.9% of these patients had organ failure. Bleeding was observed in 31.9-50.0% of DIC patients with liver disease, hematologic malignancies, and solid tumors. Organ failure was observed in 21.7-33.3% of DIC patients with liver disease, hematological malignancies, and solid tumors. Analysis by measurement of plasma levels of antiplasmin and plasmin-antiplasmin complex suggested that excessive fibrinolysis might contribute to the development of bleeding in these DIC patients. Differences in plasma levels of thrombin-antithrombin complex and cross-linked fibrin degradation products could not account for the differences in the incidence of organ failure in the patients. These findings suggest that the clinical manifestation of DIC varies and might not only be a reflection of microthrombus formation but also a reflection of the other underlying pathomechanisms.