The assessment of D-dimer concentration has become essential step during diagnostic algorithm of venous thromboembolism (VTE). This test characterizes high sensitivity but limited specificity. Negative D-dimer with high probability excludes VTE. The aim of this study was to assess the percentage of patients treated in Department of Internal Medicine, Endocrinology and Haemostatic Disorders, Medical University of Gdańisk, who in spite of clinical signs of VTE showed normal D-dimer level. Between 2000 and 2004 in our department 57 cases with recent deep vein thrombosis (DVT) were diagnosed, in 2 cases with co-existence of pulmonary embolism (PE). The D-dimer concentration was assessed in patients' plasma with the use of immunoturbidometry. Between 57 cases with VTE, 7 patients (12%) showed normal D-dimer level (<500 microg/ml). This group consisted of 4 men and 3 women, aged from 40 to 82 years (the mean age of 58 years). In all 7 cases DVT was diagnosed, in 2 patients with concomitent PE. The final diagnosis was confirmed by compression ultrasonography and pulmonary scintigraphy. Our analysis underlines the observation that occurrence of VTE and negative d-dimer concentration is possible and may probably be related to methodological limitations. However, the lack of increase of D-dimer could also be caused by fibrinolysis alteration.