A case of spontaneous non-traumatic rupture of the thoracic aorta in ahypertensive patient is presented. The clinical findings suggested acuteaortic dissection, and a large pericardial effusion was detected byechocardiography. The typical angiographic features of aortic dissectionwere not found. Autopsy revealed a longitudinal intimal tear and a rupturein the postero-lateral aspect of the ascending aorta. No false lumen wasseen in the ascending aorta. When acute intrapericardial or intrapleuralbleeding develops with no evidence of aortic aneurysm or dissection,spontaneous aortic rupture should be suspected.