Pectus excavatum occurs in two thirds of children with Marfan's syndrome. The characteristics of seven children with Marfan's syndrome and pectus excavatum were compared with those of 38 children who had pectus excavatum without Marfan's syndrome. The children with Marfan's syndrome presented later, had progressive defects, and were more likely to have wound problems; however, acceptable cosmetic and functional results after chest wall repair were obtained in the patients with Marfan's syndrome.