Among the bronchial lymphoid tissue, lympho-epithelial nodules are an original component, easily distinguished from other structures, particularly from lymphoid cell infiltrates. Such structures are encountered in many species and may be characterized as follows: they contain flattened epithelium; they demonstrate few ciliated cells; they are devoid of mucus producing cells; and they are permeated with lymphocytes. Intercellular and intracellular vacuoles are described in the lympho-epithelium and the underlying mucosa. EM studies showed that lymphoepithelium has a trapping function for particulate matter. Peripheral lymphatic vessels and high endothelium veins contribute to the important lymphocyte transfer. The capacity for antigenic recognition by the lymphoepithelial nodule is discussed.