Three cases of pulmonary hypertension caused by tumor emboli to the lungs are described. Two of the three cases had a clinical diagnosis of pulmonary thromboembolism until surgical embolectomy, and the other had a diagnosis of primary pulmonary hypertension. Autopsy disclosed chondrosarcoma, choriocarcinoma and gastric cancer as the primary tumors, respectively. Pulmonary vascular obstruction due to tumor embolism leading to pulmonary hypertension is a previously rare clinical entity, and obstructed pulmonary vessels are believed to tend to be small vessels. We compared the autopsy and radiological findings and concluded that pulmonary tumor embolism involved not only the small peripheral arteries but also the segmental and/or lobar arteries.