43-year old woman, with considerable overweight had been admitted to Intensive Medical Care Unit with suspicion of pulmonary embolism (PE). The patient had the limb immobilized in gypsum for last several weeks. This episode was tangled with recurrent thrombosis of deep veins in the left limb, treated with heparin and oral anticoagulants irregularly without sufficient control. Taking into consideration the data of anamnesis, clinical picture and the results of ECG, chest X-ray, gasometric and echocardiographic examination we got much closer to the recognition of PE. Our suspicion of PE was confirmed by the result of pulmonary angiography. Indications for thrombolytic treatment (r-tPA) had been established. During the following hours considerable improvement of general state was observed. The therapy was continued with constant drip infusion of heparin. No prolongation of therapeutic PTT was observed. The deficit of AT III was diagnosed. In this situation the patient was given AT III to obtain normalization of its level and therapeutic extension of PTT. Therefore there were settled indications for the operation of uterus with myoma changes. As the rich thrombolytic material in the leg's vein was found the patient was implanted LGM Filter, with excellent prophylactic effect (no PE in perioperative period). The clinical course of our case enabled to present most of diagnostic, therapeutic and preventive methods applied in venous thromboembolism.