Hemostasis was studied in 70 patients with gastric or intestinal cancer. Pronounced imbalance in blood coagulation was established, resulting in chronic disseminated intravascular coagulation (DIC) syndrome in 55.7 and thrombophilia--in 20% of cases. Advancement of tumor to stage IV was followed by development of stage II (subacute) DIC syndrome. The syndrome was frequently manifested by thrombohemorrhagic complications which occurred in 14.5% of cancer patients (autopsy data). It was inferred that timely treatment of malignancies, early administration of heparin, fibrinolysis--activating drugs and deaggregants are pathogenetically justified means for prevention and treatment of DIC syndrome.