Between 1988 and 1994, 295 patients with blunt chest trauma were treated. Forty-two patients had flail chest, requiring mechanical ventilation. Open reduction and osteosynthesis (ASIF reconstruction plates or isoelastic rip clamps) of the chest wall were performed in 20 patients. For the purpose of analysis we separated the patients into five groups: group I (n = 10) had chest wall stabilization in flail chest without pulmonary contusion (average ISS 31.0, AIS-thorax 4.1); group II (n = 10) had chest wall stabilization in flail chest with pulmonary contusion (average ISS 37.0, AIS-thorax 4.3); group III (n = 18) had fail chest without pulmonary contusion (average ISS 36.3, AIS-thorax 4.2); group IV (n = 4) had flail chest with pulmonary contusion (average ISS 37.8, AIS-thorax 4.0); group V (n = 29) had pulmonary contusion without flail chest (average ISS 34.5. AIS-thorax 4.1). With open reduction and internal fixation of unstable chest wall segments, the duration of ventilatory support, mortality and pneumonia were significantly reduced to 6.5 (1-25) days in group I (mortality rate 0%, incidence of pneumonia 10%) compared to group III (duration of ventilatory support 26.7 days, mortality rate 39%, incidence of pneumonia 16%). Eighty percent of the patients in group I were extubated within 5 days postoperatively. In group II 4 patients underwent emergency thoracotomy for intrathoracic injuries (3 of them died between 4 h and 31 days) and 2 patients for laceration of the lung. In all these cases the chest wall was stabilized after thoracotomy. One patient was stabilized for a deformation of the chest wall and two for paradoxical movement of the chest wall during weaning from the respirator. The mean duration of ventilation in group II was 30.8 (10-112) days (mortality rate 30%, incidence of pneumonia 30%). No complications related to the osteosynthesis arose during the follow-up. In conclusion, the best indication for early operative chest wall stabilization is flail chest without pulmonary contusion, leading to a significant reduction in the duration of ventilatory support. Secondary stabilization is recommended in patients with pulmonary contusion showing paradoxical movement of the chest wall during weaning from the respirator.