The use of prolonged mechanical ventilation in the treatment of flail chest injury may increase the incidence of pulmonary morbidity. The aim of this study was to examine the results of performing internal pneumatic stabilization in our hospital. A retrospective review of the medical records of 59 patients with flail chest injury who presented within an 11-year period was conducted. During the second half of the period examined, we routinely adopted three characteristic procedures in the treatment of flail chest injury, namely, pressure support on spontaneous breathing, continuous positive airway pressure via a mask, and respiratory physical therapy by physical therapists. We compared the background, prognosis, and methods of treatment for flail chest injury before and after the introduction of these three procedures. A marked decline in the duration of endotracheal intubation and controlled mechanical ventilation, and in the frequency of pulmonary morbidity, was evident following the introduction of the above procedures.