We report 2 cases of pulmonary hypoplasia diagnosed in adulthood presenting clinically as chronic respiratory failure. Both patients met criteria for chronic bronchitis and had shown repeated respiratory infections and increasing dyspnoea. The spirometry showed a severe non-defined ventilatory disturbance and the arterial blood gases showed the presence of marked hypoxaemia. The altered chest X-ray, arterial blood gases and spirometry had been attributed to chronic bronchitis. The CT scan was instrumental in establishing the diagnosis of pulmonary hypoplasia.