Cardiovascular abnormalities are the most common cause of death in patients with the Marfan syndrome, and a variety of lesions have been described in the aorta and heart in such patients. Although some information has been reported in at least 151 necropsy patients with the Marfan syndrome, 1-g1 no studies are available describing in detail large numbers of such patients at necropsy. Indeed, of the 151 necropsy patients reported, 65 were isolated case studiesl-5, 7, 6, 10-12, 14, 15, 18, 20, 23-26, 28, 29, 31-36, 38-41, 43-51, 54, 56-62, 64.70, 72-75, 79.60, 65, 67-99, 91; each of 14 reports described only two patients 6, 9, 13.16, 17, 21, 22, 30, 63, 71, 76-78, 81, 83., each of three reports described three patients1s~ 37~ 53; three reports described four patients52* 84* 90; and five reports described five, 86 six, 27, 55 seven, 42 and 11e2 patients, respectively. The amount of detailed information available on each necropsy patient tended to be much less in the reports describing more than two patients than in those concerned with only one or two patients. Although virtually all of the previously reported necropsy patients with the Marfan syndrome had characteristic musculoskeletal features of this syndrome, 6Z not all had histories of this syndrome in other family members or the characteristic ocular features. 82 To determine more precisely the type and frequency of the cardiovascular lesions in the Marfan syndrome, this report reviews findings in 18 necropsy patients with this syndrome studied in the Pathology Branch, National Heart, Lung and Blood Institute, and compares the observations in them to those in previously reported necropsy patients.