Lung tissue from 20 patients undergoing resection for a peripheral carcinoma was studied using monoclonal antibodies to identify inflammatory cell types in the peripheral airways and to determine the location of the bronchial-associated lymphoid tissue (BALT). The patients were grouped according to their percent predicted FEV1 (%FEV1) into obstructed (%FEV1 less than 80%) and control (%FEV1 greater than 80%). The resected lungs were filled with dilute cryoembedding media (Tissue-Tek R), frozen over liquid nitrogen, sliced into 2-cm sagittal slices using a band saw, and sampled using a cork bore. Ten serial histologic sections cut from these samples were stained with monoclonal antibodies for specific inflammatory cell types, which were counted and expressed per square millimeter of airway wall area. The results showed that the patients with airway obstruction had more B-lymphocytes in the airway adventitia than did the control subjects (p less than 0.001) and that the number of submucosal polymorphonuclear leukocytes is related to the amount smoked (p less than 0.02). They also show the BALT has a different distribution in human than in rodent lungs in that the lymphoid collections are found in the outer walls of the airway rather than in the submucosa.