1. The regional distribution of ventilation was studied with 133Xe techniques in the sitting position in six patients with complete traumatic transection of the cervical spinal cord, 3–40 months after the lesion, and in four normal subjects. The relative contributions of the rib cage and abdomen to ventilation were determined from chest-wall motions. 2. Total lung capacity (TLC) was decreased and residual volume increased in the patients. After correction for the decreased TLC, the distribution of the regional functional residual capacity in the tetraplegic patients was similar to that of the normal subjects. In the patients, where the abdomen contributed to about half of the tidal volume, decreased ventilation of basal regions was demonstrated from measurements of regional tidal volumes (Vtr) and regional 133Xe wash-in curves. 3. The distribution of ventilation in normal persons, however, was not changed by varying the relative contributions of the rib cage and abdomen to the tidal volume, as shown from Vtr and regional 133Xe wash-out measurements. 4. The results in the tetraplegic patients are interpreted as evidence of ‘small airway disease’, presumably from infection of the air way and impairment of the cough.