The content of D-dimer was studied in 130 patients with cancer at various sites. Twenty-five patients were diagnosed as having pulmonary thromboembolism (PTE), 30 had venous thromboses, and 35 patients had acute and subacute disseminated intravascular coagulation (DIC) syndrome. A control group included 40 patients without thrombotic complications. The studies were performed on an automatic STA COMPACT analyzing device. It has been shown that there is a drastic (10-15-fold) increase in the content of D-dimer as compared with the controls. The highest level of D-Dimer was observed in patients with acute DIC who have significant clinical symptomss. The level of D-dimer was to a lesser extent increased in patients with multiple organ deficiency. The content of D-dimer decreased during therapy anticoagulant therapy. When PTE, venous thrombosis, or DIS are suspected, it is advisable to include the study of D-dimer into a coagulogram.