Patients with portal hypertension of varying etiology may develop pulmonary artery hypertension. In the present autopsy study, pulmonary and hepatic tissue was studied in 12 patients in whom pulmonary and portal hypertension coexisted. Plexogenic pulmonary arteriopathy was present in 10 patients, 7 of whom had coexistent thromboembolic lesions. One patient had isolated medial hypertrophy, which may be an early stage in the plexogenic category, whereas isolated thromboembolic pulmonary vascular disease was observed in one subject. Hepatic disease was consistent with alcoholic cirrhosis in seven patients, cryptogenic cirrhosis in four and extrahepatic portal hypertension without cirrhosis in one. Thrombocytopenia was present in all 10 patients whose platelet count was determined. This study suggests that pulmonary hypertension associated with portal hypertension commonly has a plexogenic appearance on histologic examination. However, thrombosis (whether embolic or in situ) may also contribute to vascular obstruction.