Middle lobe syndrome (MLS) or atelectasis syndrome can affect any pulmonary lobe but occurs more frequently in the right middle lobe. Only 15 per cent of the reported cases are children. We report two cases of MLS in two boys of 4 and 12 years of age who were referred to our institution because they had suffered from recurrent pneumonies of the right middle lobe for ten months and six years respectively. We performed chest radiographs, computed tomography scanning, ventilation-perfusion scintigraphy and flexible bronchoscopy. The evolution in both cases to an atelectasic middle lobe with pulmonary shrinkage and lack of perfusion was the indication to lobectomy. Histological examination showed a bronchial obstructive process in the young patient and a chronic non specific inflammation of the pulmonary parenchyma in both. The resection brought about a cure. The identification of MLS is usually a late diagnosis. Thus, if atelectasis persists after an adequate medical therapy, resection of the lobe is indicated.