The Marfan syndrome is frequently complicated by cardiovascular abnormalities. Of these, aortic dissection and aortic valve regurgitation are the most life-threatening. The most noticeable abnormalities of the Marfan syndrome--the skeletal abnormalities--may be subtle and limited. Presented here are five reports of cases of the Marfan syndrome. All patients had potentially lethal cardiovascular complications. Either the syndrome had not been previously diagnosed or the patient had not been adequately monitored despite the the presence of thoracic cage deformities present from youth. The purpose of this report is to heighten recognition of the association of thoracic cage deformities with the Marfan syndrome to permit early diagnosis of the associated cardiovascular complications. Surgical management of these complications can favorably alter the natural history of the Marfan syndrome.