The effect of starvation on postnatal lung growth in rats was investigated. Litters were starved twice, each time for 24 hours, on Day 1 and Day 5 after birth. One group of littermates was sacrificed on Day 7, and another group, on Day 14 of postnatal life. Intermittent starvation diminished lung growth. This was accompanied by reduced somatic growth. On postnatal Day 7, lung volume, total number of alveoli, and internal surface area of the lung were decreased in starved rats, but structurally their lungs appeared similar to control lungs. On postnatal Day 14, a striking morphologic difference was observed between the lungs of control and starved pups. Following starvation, retardation of lung growth was manifested in all the parameters studied. One week of normal uninterrupted suckling could not overcome the starvation-induced initial effects on growing lungs. It is concluded that starvation, soon after birth, affects adversely the normal development of lung.