The basal metabolic rate (BMR) of infants with growth failure of prenatal onset who had either recognized dwarfing syndromes or a growth pattern suggestive of primordial dwarfism, with or without congenital anomalies, was low in comparison with that of normal height controls. They did not respond to feeding in the hospital. Infants with growth failure of postnatal onset had much higher values, equal to normal height controls; such patients had growth failure