The risk of pulmonary embolism associated with the proximal portion of the thrombus varies depending on its structure. The objective of the present work was to evaluate the risk of pulmonary embolism in patients presenting with a structural variant of the proximal portion of the thrombus traditionally regarded as creating the risk of pulmonary embolism. The prospective study included 220 patients at the age from 29 to 78 (median 57) years with clinical manifestations of thrombosis during a period from 1 day to 3 months. They had a venous thrombus with the proximal portion located either in the superficial or in the common femoral vein. This portion was up to 4 cm long, had a wide base commensurate to the vein diameter and high echo density. All the patients wee treated by compression and anticoagulation therapy following the standard protocols without prophylactic surgical interventions. The propagation of the thrombus in the proximal direction was documented in 2 (0.9%) of the 220 patients. One (0.5%) patient presented with pulmonary embolism that necessitated thrombolytic therapy. The cause of the single fatal case (0.5%) was massive pulmonary embolism that had developed before admittance to the hospital. The results of the study suggest the low risk of pulmonary embolism in patients with the thrombus in the femoral vein having the proximal portion with the above characteristics. The authors propose to refer this variant to a separate group of dome-shaped thrombi to be treated by adequate anticoagulation therapy without surgical intervention.