Two patients are described who had the body habitus of the Marfan syndrome, cutaneous hyperextensibility, and atrophic "cigarette paper" scars. One had mild joint hypermobility and the other had generalized ligamentous laxity. Both individuals are considered to be examples of the Marfanoid hypermobility syndrome, a generalized heritable connective tissue disease with features of, but genetically distinct from, the Marfan and Ehlers-Danlos syndromes. One patient had a "floppy" mitral valve and the other had an aortic aneurysm due to cystic medionecrosis of the aorta; both findings provide evidence that cardiovascular disease may be a significant feature of this syndrome.