Pulmonary artery dissection was observed in a 64-yr-old female patient with severe pulmonary hypertension, which was probably primary (pulmonary vascular resistance, 817 dyn.s.cm-5; normal range less than or equal to 200 dyn.s.cm-5). The patient was admitted to the hospital because of severe dyspnea on exertion. Echocardiography demonstrated a dissecting aneurysm of the pulmonary artery. Right heart catheterization revealed severe pulmonary hypertension (mean pulmonary artery pressure, 64 mm Hg; normal range, 10 to 22 mm Hg); dissection of the pulmonary artery was confirmed by pulmonary arteriography. One-year follow-up was uneventful. In the literature, 28 patients with dissecting aneurysm of the pulmonary artery are reviewed. The dissection has only been diagnosed in life in one patient (by echocardiography).