Objective To detect the changes in blood coagulation system and clarify the related mechanisms of chemotherapy-induced disseminated intravascular coagulation.Methods　Changes in blood coagulation system and immunohistochemistry for fibrinogen were investigated in six groups of rats designed for different purposes.Results　Decreased platelet count, prolonged prothrombin time and active partial thromboplastin time, elevated fibrinogen level, and decreased antithrombin were observed in the rats receiving a newly developed chemotherapy (NDC group), in which mitomycin C was administered intravenously together with angiotensin. Accumulation of fibrinogen and microthrombi in the blood vessels of multiple organs were also found in the NDC group by immunohistochemistry and histopathological examination.Conclusions　Rapid reduction of tumor mass induced by an effective chemotherapy could cause hypercoagulable state and disseminated intravascular coagulation.