We banded the trachea of 4-wk-old male rats and studied lung growth, lung morphometry, and static pulmonary mechanics 4 wk later. We compared the experimental animals to sham-operated male littermates of the same age, 8-wk-old normal male littermates, and weight-matched rats of a younger age. Tracheal banded animals were smaller and had significantly smaller absolute lung volumes fewer alveoli, larger interalveolar wall distances, and increased alveolar duct size compared to the other groups. Their lung volumes were significantly smaller than were those of weight-matched controls. Air-filled pressure-volume curves from the tracheal ligation group were shifted to the left and upward when expressed as a percentage of total lung capacity or by fitting exponentials to the pressure-volume curves. There was no difference in saline-filled pressure-volume curves. We conclude that tracheal banding slows somatic growth and alters normal lung growth. Loss of elastic recoil appears to be due to alteration of surface forces.