Background. A case of potentially fatal pulmonary embolism after a hip arthroplasty is discussed. Early diagnosis and immediate treatment rescued a patient’s life. The risk factors of pulmonary embolism, its symptoms and employed treatment to save the patient are assessed. Case report. A 62-year-old male was hospitalized due to left hip arthrosis and a total hip replacement was successfully performed. Standard peri-operative antithrombotic prevention with s.c. injections of low-molecule heparin was introduced. Early post-operative period went without uneventful and rehabilitation was started. On the 5th postoperative day increasing weakness, breathlessness and a collapse incident occured. Subsequently massive pulmonary embolism, in spite of slight clinical symptoms, was diagnosed. The lab result of D-Dimers appeared particulary useful in the diagnosis. CT scanning of the chest with an angio-CT option definitively confirmed the diagnosis. On the 6th day, after a hip arthroplasty a cardiosurgical operation of pulmonary embolectomy was successfully performed. Doppler USG examination showed a left popliteal vein as a potential source of intravascular clot, which might cause the embolism. After the embolectomy antithrombotic treatment with heparin in permanent i.v. infusion was employed first followed by therapy with Acenocumarol. Antithrombotic therapy and rehabilitation made the patient get physical fitness. The patient was discharged home ambulatory in a general good condition. Conclusions. Many risk factors in the same patient, despite of standard, peri-operative, antithrombotic therapy with fraction heparin, may contribute to occurrence of pulmonary embolism, especially when a large joint of a lower extremity was operated. In the opinion of authors the pulmonary embolism that occur earlier than usually might be related to peri-operative, antithrombotic therapy, which might free preexisting thrombi into circulation. In view of such hypothesis the patients with the high risk of pulmonary embolism should be examined with Doppler USG test of lower limbs prior to planned surgical treatment.