Thoracic trauma is uncommon in children. It should not be managed any more as adult's trauma. We present our experience with 85 children form 1 to 16 years of age, presenting severe thoracic trauma treated in Lausanne, Switzerland, between 1976 and 1990. The specific features of diagnosis, treatment and outcome are presented. Most of them were involved in traffic accidents (62%), 55% had multisystemic injuries. The mortality rate was not a function of the Injury Seventy Score as in adults, but was only related to the Glasgow Score. Only 3 patients (3.5%) had hemodynamic instability on admission in relation with their thoracic injury. Patients with intrathoracic lesions showed dyspnoea (65%), cyanosis (25%), or clinical suspicion of a pleural effusion or a pneumothorax (47%). However 12 children had an asymptomatic severe thoracic injury. In 53 patients (62%) the auscultation was found abnormal either with absent or diminished breath sounds or other pathological findings. 10 out of 26 cases of pneumothorax could be suspected by percussion dullness. Chest X-rays showed a lesion in 76% of cases. Only 30% of the pneumothorax were associated with visible rib fractures. 10 children suffered from 4 to 12 fractures of the ribs (mean 6.6). None of these patients presented a flail chest as in adults, even when multiple rib fractures existed. 31 thoracic drainages were performed, during a mean period of 3.3 days. 30 patients were intubated and ventilated, 22 of these due to a neurosurgical condition. All patients had physiotherapy starting on day 2, under analgesia if necessary.(ABSTRACT TRUNCATED AT 250 WORDS)