Lung involvement occurred in 43% of 284 patients with Hodgkin's disease in Nottingham during 1960-75. It was commoner than pleural, hilar or mediastinal node involvement, although over three-quarters of patients with any other thoracic manifestation subsequently developed pulmonary involvement. The patients with pulmonary involvement contained significantly fewer with the histological feature of lymphocyte predominance. The commonest radiographic type, peribronchial infiltration, tended to occur early in the course of the disease while less common types, homogeneous or pneumonic infiltrates and nodules, occurred later. Modern chemotherapy was very effective in the treatment of pulmonary Hodgkin's disease. Since two-thirds of the patients who developed lung involvement already had stage IIIB or IV disease, the early use of chemotherapy should reduce the incidence of this common complication.