The results of treatment of 78 patients, operated in the clinic in 2008-2010 yrs, are adduced. The sensitivity, specificity and the precision values were determined for diagnostic method in deep veins thrombosis (DVT). The method was based on investigation of the products of degradation content of the transversely-sutured fibrine (D-dimer) and its dynamics in the blood of patients. D-dimer was determined, using express-method of the erythrocytes agglutination identification with application of SimpliRED technology in the whole blood. In 16 (20.5%) patients DVT was revealed within vena cava inferior basin, of them in 7 (43.7%) patients the course of thrombosis was asymptomatic, and the disease presence have had become suspected after obtaining of the D-dimer test positivity and was confirmed by ultrasonographic angioscanning. In 43 (55.1%) patients of the investigated group the D-dimer test positivity was noted. In all the patients, suffering phlebothrombosis, the test was extremely positive, presented by the erythrocytes agglutination on the 5-20th second and long-term presence of D-dimer during (17 +/- 6) days, at average. In 14 (87.5%) patients the application of direct anticoagulants was stopped after the test negative results obtaining. Rethrombosis and pulmonary artery thronboembolism (according to clinical investigation) did not occur.