Aim. To study the factors associated with elevated D-dimer levels in patients with acute venous thromboembolic events (VTEE). material and methods. The study included 111 patients (76 men and 35 women aged 18–76 years) with a first or repeat episode of deep vein thrombosis (DVT) and/or pulmonary embolism (PE) in the last 2 months. The majority of the patients (n=80) received unfractionated heparin (UFH) for at least 5 days, followed by warfarin (international normalized ratio (INR) control at least once a month; target INR 2,0–3,0). Some patients (n=31) received therapeutic doses of enoxaparin (1 mg/kg subcutaneously, every 12 hours) for at least 30 days, followed by warfarin treatment. D-dimer levels (norm ® D-DI” reagents (Diagnostica Stago). Results. D-dimer levels varied from 0,02 to 9,96 mkg/ml (median 1,05 mkg/ml, interquartile range 0,49–1,99 mkg/ml) and exceeded the upper norm limit in 74% of the patients. There was a positive association between D-dimer levels and thrombus “size” (r=0,304; p < 28 days, and thrombus “size” < 6 points were independent predictors of D-dimer elevation in the acute period of DVT/PE. Conclusion. D-dimer levels, measured 32 (23–44) days after the development of DVT/PE symptoms, were elevated in 74% of the patients. D-dimer elevation in the acute period of VTEE was associated with female gender, CHF, “age” and “size” of the thrombus.