The pulmonary manifestations of 5 biopsy-proved cases of lymphomatoid granulomatosis are discussed. Two patients had diffuse reticulonodular infiltration of the lungs, thought to represent infiltrates of lymphomatoid granulomatosis. Three had nodular densities of varying size and distribution, with radiologically normal intervening lung, and biopsy suggested that these represented infarcts; the actual infiltrates of lymphomatoid granulomatosis were below the limits of resolution of the chest radiograph.