Some histological signs of congenital lung malformations are described basing on many years' studies including those carried out in cooperation with pediatric surgeons. Histological signs of congenital malformations comprise rugged, "cut up" bronchiectatic lumens due to pseudopoliposis, diverticulosis and abundancy of Lambert tubes. In bronchiectatic lumens there may be openings of smallest bronchi, bronchioles or alveoli, indicating the absence of several bronchial generations, and reflecting the replication of filogenic development of the lung. In addition to agenesia of the alveoli, in the place of which connective tissue is found without twisting elastic fibres in it (such fibres being characteristic of the acquired fibroatelectasis), areas with conglomerates of bronchioles may be seen. Histologically, they are often misinterpreted as adenomatous structures. Inclusions of normal structures may provide proper functioning of the lung throughout the patient life, till the old age. Therefore, the prognosis with the developmental anomalies in the lung will be influenced considerably by the quantity of the malformed bronchi present.