A 41-year-old man presented to the emergency department complaining of dyspnea and left-sided pleuritic chest pain. He had been admitted and treated for pulmonary thromboembolism 10 years ago. However, he stopped the medication in 6 months. His both legs were swelling with pitting edema. Laboratory results showed an elevated D-dimer serum level (6.3 ug/mL, normal <0.55). Anticardiolipin antibodies and lupus anticoagulant were not detected. Protein C and protein S levels were normal. Electrocardiogram showed sinus tachycardia, right ventricular hypertrophy. Chest computed tomography revealed thrombus in the enlarged main pulmonary trunk, left lobar branch and total occlusion of right middle and lower lobar branch (Fig.1).Echocardiography showed a right ventricular overloading sign with severe pulmonary hypertension (pressure gradient 158 mmHg), severe tricuspid regurgitation, and D-shaped left ventricle(Fig. 2). The patient received standard anticoagulant. Computed tomography of venogram showed diffuse thrombus at inferior vena cava (IVC), from suprarenal IVC to iliac vein to femoral vein to popliteal vein to calf veins. After a 20-day course of hospital treatment, IVC venogram showed no visible thrombotic filling defect at IVC and right femoral vein. but left femoral venous flow was sluggish. Lower legs Doppler ultrasound didn`t revealed visible thrombus. He still had pulmonary hypertension (85mmHg) at the end of 2 months follow-up. However, the patient`s symptom improved and continued taking oral anticoagulation therapy.