A 38-year-old female is described, who was admitted with increasing respiratory distress, cough and visible blood stasis in the jugular veins. The most likely diagnosis in this young women taking oral contraceptives was pulmonary embolism, however, a ventilation-perfusion lung scan was normal. Echocardiography showed a dilated right ventricle and increased systolic pulmonary pressure. Despite administration of oxygen and intravenous heparin the patient died in circulatory collapse before further investigations could be initiated. Post-mortem examination revealed diffuse adenocarcinoma of the stomach (linitis plastica) with metastasis to local lymphnodes, lymphangiosis carcinomatosa of the liver, pancreas and spleen and tumour cell masses within the lumen of small pulmonary arteries leading to variable occlusions of the vessels. Fibrocellular intimal proliferation was found, leading to further obstruction and increased resistance to flow through the pulmonary vascular bed and to subacute cor pulmonale.