Open reduction and osteosynthesis with AO (Arbeitsgemeinschaft fur Osteosynthese) technique, using 3.5 mm reconstruction plates and 3.5 mm cancellous screws, were performed in all cases of chest wall injury considered for surgical stabilization since 1990, viz. 11 with posttraumatic flail chest and one with painful nonunion of two ribs. In the ten survivors with flail chest, stability was achieved without secondary dislocation, giving good pain relief, improved respiratory mechanics and reduced duration of ventilatory support and intensive care requirements. Lasting pain relief was obtained also in the case of costal nonunion. No complications related to the osteosynthesis arose during follow-up for a mean of 11 months. Chest wall injuries in flail chest and painful nonunion of ribs can be easily and efficiently stabilized with the AO technique.