The adequate implementation of the programs of long-term beam chemotherapy implies that the patients not infrequently need permanent venous access. To meet this requirement, the totally implanted continuous venous access port systems are inserted to operate for the extended length of time. However, these devices are known to create the high risk of the development of venous thromboembolism (VTE). Specifically, around 15% and 4.5% of the patients have been reported to suffer from thrombotic complications and pulmonary embolism respectively. Taking these facts into consideration, certain hospitals elaborate and implement the active thrombosis monitoring programs. Therefore, the objective of the present study was to evaluate the frequency of venous thromboembolism in the patients treated with the use of these implantable systems. Material and methods. To carry out the extended chemotherapy, the totally implanted continuous venous access systems were inserted under the control of computed tomography to 105 patients during the period from 2013 to 2016 . The age of the patients ranged from 27 to 61 (mean 45) years. Each patient who had undergone such intervention was regularly examined during visits to a surgeon (on months 1, 3, and 6) with the use of ultrasound scanning of the superior vena cava and subclavian veins and of echo-cardiography. In addition, CT angiography of the pulmonary arteries was performed in the cases of suspected pulmonary embolism. Results. Fourteen (13.3%) patients developed acute thrombosis in the superior vena cava system within the first three months after the implantation. These patients were treated with low-molecular weight heparins at therapeutic doses. Local thrombolysis with the aspiration of the active thrombotic masses turned out to be successful in three cases. Two other patients failed to develop re-canalization and were found to be at risk of the progressive thrombotic process; for this reason, their implanted port systems were removed. The mean time for the development of thrombosis was 3 months after the intervention. A single case of pulmonary embolism was documented during the study period. Conclusion. Venous thromboembolism is a frequent complication of chemotherapy with the application of the totally implanted continuous venous access systems. Active VTE monitoring in oncological patients treated by this method is an important part of disease management. The active strategy intended to promote the re-canalization of the port system and the venous bed makes it possible to continue the specialized treatment of the underlying disease.