Twenty-four patients with severe lung contusion and multiple rib fractures were studied at a mean 4.9 years (range 2-9 years) after injury. All patients had been in good health before the accident. After the accident 15 (63 per cent) patients had respiratory symptoms such as dyspnoea at rest or moderate exercise (4), pain (8), cough or increased expectoration (11) and frequent bronchopulmonary infections (5). Three patients had changed their job because of respiratory disturbance. The average vital capacity, forced expiratory volume in 1 s, maximal voluntary ventilation and CO transfer factor were reduced respectively to 87, 88, 82 and 83 per cent of predicted values (P less than 0.01), while total lung capacity, residual volume and helium mixing time showed no definite changes (P greater than 0.05). Arterial blood gases at rest and at maximum exercise showed slight changes only. Maximal working capacity and ECG, as well as the ventilatory cost of moderate exercise were normal, where as the CO2 recovery time after moderate exercise was slightly increased (P less than 0.05). Overall there was a tendency towards poorer function in patients treated with artificial ventilation. Chest radiographs were normal in 10 patients (42 per cent), and moderate changes were seen in 14 patients. Diaphragmatic movements were essentially normal in all patients. Severe injury to the chest causes frequent respiratory symptoms. However, objective tests were only moderately reduced when compared with normal values. There was no unequivocal association between the subjective symptoms and the pulmonary function.