The medical records of 114 infants with abdominal wall defects, including 35 infants examined at autopsy, were reviewed to determine if giant (liver-containing) defects are associated with a narrow thoracic cage deformity and pulmonary hypoplasia. The study included 48 infants with gastroschisis, 60 with omphalocele, two with a lower midline syndrome (cloacal exstrophy) and four with an upper midline syndrome (Cantrell's pentalogy). A giant abdominal wall defect was present in 33 infants, including one with gastroschisis, 27 with omphalocele, two with a lower midline syndrome, and three with an upper midline syndrome. A thoracic cage deformity, characterized by a narrow chest and down-slanting ribs, was identified radiographically in 42% (14 of 33) of infants with giant abdominal wall defects. Among the 35 infants examined at autopsy, 14 infants with giant omphaloceles had mean chest circumference to occipital frontal circumference ratio and lung weight to body weight ratios that were significantly below the means for infants with gastroschisis or small omphalocele. Lung weight to body weight ratios indicated marked pulmonary hypoplasia in three of 12 (25%) of infants who had a narrow thoracic cage deformity, and radial alveolar counts indicated mild pulmonary hypoplasia in four additional infants. Prematurity (four infants), diaphragmatic abnormalities (seven infants), and congenital heart disease (four infants) potentially contributed to the respiratory distress experienced by these 12 infants. Infants with giant abdominal wall defects and narrow thoracic cages are at increased risk for pulmonary hypoplasia and respiratory distress.