Introduction. The aim of this study was to investigate the role of duplex Doppler ultrasonography in diagnosis of deep venous thrombosis (DVT) of the lower extremities. Material and methods. During a 2-year period, 860 patients were examined by duplex Doppler sonography. Among these, 619(72%) were women and 241 (28%) men, with the age-range of 16-91; (mean 56,2) years. Siemens Versa Pro color doppler was used, with 7MHz transducers. Findings were categorized into four categories: 1. deep venous thrombosis (DVT); 2. pathology predominantly related to superficial veins without DVT; 3. pathology of superficial and deep veins; 4. normal findings. Results. 185 (21%) patients had DVT, 366 (42.5%) patients had pre?dominant pathology of superficial veins: postthrombotic syndrome, superficial thrombophlebitis and varicose veins. 128 (14.9%) patients had pathology of superficial and deep veins. Normal findings were found in 181 (21.1%) patients. Conclusions. Various vascular and nonvascular diseases may mimic deep venous thrombosis, and that is why US should be used whenever possible to avoid unnecessary anticoagulant therapy. .