Six hundred eighty-five patients with major blunt thoracic injuries from 1968 through 1977 were retrospectively studied. This series was compared to a similar series from 1959 through 1964. Between 1964 and 1968 a vastly improved hospital was built, laboratory support improved, pressure-controlled ventilators replaced by volume-controlled ventilators and the trauma service was reorganized. The treatment regimen for flail chest injuries during the last decade evolved from the previous early tracheostomy and prolonged ventilator support to an avoidance of tracheostomy and brief ventilator support. The overall mortality in the present series was 20% compared to 35% for the 1959-1964 series; however, improved mortality occurred only among patients with hemothorax who had one or more major concomitant extrathoracic injuries. The mortality for flail chest injuries did not improve (29.5 vs 35.0%). Mortality was unchanged for isolated flail chest injuries, isolated pneumothorax, isolated hemothorax, and for flail chest injuries, and pneumothorax in patients with concomitant major extrathoracic injuries. In both series deaths from isolated thoracic injuries were rare. It is evident that the continued high mortality for blunt thoracic trauma principally relates to concomitant extrathoracic injuries and that recent treatment innovations have not reduced the mortality of flail chest injuries.