Several cardiologic pathologies are seen in infants of diabetic mothers (IDMs). Though asymmetrical septal hypertrophy (ASH) is a frequent pathology in IDMs, it is not routinely searched for with an echocardiographic scan. We have performed an echocardiographic examination for all IDMs (56 neonates) hospitalized between January 1987 and December 1992 in our neonatology and neonatal reanimation units. Of 56 patients, the diagnosis of 17 cases of ASH (30%) was made. The group with ASH (17 neonates) had a greater corporeal index than the group without ASH (39 neonates) (p < 0.05). Four of the 17 IDMs (24%) with ASH and one of the 39 IDMs (3%) without ASH presented with a cardiac insufficiency (p < 0.05). ASH is a pathology which should be searched for routinely in IDMs.