The specific compliance of the chest wall and lungs combined was measured in eight patients with stable tetraplegia. Expiration was impeded with a series of spring-loaded resistances, and end-expiratory pressures plotted against changes in chest wall volume at end-expiration. An optical contour mapping system was used to partition changes in chest wall volume into rib cage and abdominal components. These measurements suggest that the compliance of the whole system is reduced by one third in patients with stable tetraplegia, compared with normal subjects. This may be because of abnormal stiffening of the rib cage.