Thromboembolic disease is a potentially severe pathology.When its clinical feature implies a massive occlusionof the arterial pulmonary tree and a cardiac failure is ensued,it can be seriously life threatening even for youngpatients. Less frequent features as right or left atriumthrombosis could increase morbidity and mortality of thisdisease.We report a case of massive right pulmonary embolism(PE) with entrapped thrombus in patent foramen ovaleand right heart failure in a 32- year-old man. Transthoracicechocardiography showed a right atrial thrombusattached to the inter-atrial septum. Following the diagnosisof right heart thrombosis with massive PE, infusion oftissue type plasminogen activator (100 mg in two hours)was administered. Echocardiography performed two daysafter thrombolysis showed a significant decrease in theright ventricular size and complete lysis of the thrombusin the right heart. By genetic examination, he proved tohave factor V ’Leiden’ gene and two thrombophilia genes,all of which were positive in the heterozygous state. Hehad also a high serum homocysteine.Key words: pulmonary embolism, hypercoagulable state,thrombolytic therapy, patent foramen ovale