The relationship between malignant tumors and blood coagulation disorders is generally well known. The authors studied blood coagulation in patients with colorectal cancer and evaluated some prothrombotic markers. The authors analyzed by latex-aglutination method, ProC Global test, Asserachrom PAI-1 test and Enzygnost F 1+2 test the group of 137 patients with malignant tumor of colon and rectum, drew attention to the relationship between level of D-dimer, PAI-1, F 1+2, Protein C and the progress of malignant tumor, its localization, clinical stage, histopathology type, method of surgery considering the stapling use. Very aggressive and advanced tumors have significantly higher level of D-dimer, plasminogen activator inhibitor I (PAI-1). Prothrombotic fragments 1+2 were significantly higher by anastomosis dehiscence. Protein C level was lower in the age from sixty to seventy and in advanced clinical stage. Pre-operative surveys of D-dimer, PAI-1, prothrombotic fragments and Protein C give informations about risk of thrombosis of malignant diseases, their clinical stage and histological type. D-dimer and PAI-1 have a real clinical value and can be reliable prothrombotic marker.