Congenital lobar emphysema has been described under various designations. Although the etiology is not clear, some form of bronchial obstruction has been documented in about 50% of the patients. A rare case of congenital lobar emphysema with a membranous septum in the left main bronchus is described. Although prompt lobectomy has been the treatment of choice in most cases, this case demonstrates the importance of early bronchoscopy to exclude treatable intra luminal abnormalities.