Previous investigations of airway disease in rheumatoid patients have been oriented toward establishing the prevalence of the disease, but the pathogenesis and the time course of the airflow obstruction in rheumatoid disease are still unclear. In this study, we analysed the clinical, serial pulmonary function and histopathologic data of six rheumatoid patients who had never smoked but who had airflow limitations documented repeatedly up to 10 years previously. We have attempted to characterize the site, nature and evolution of the chronic airway disease in this group of patients. Bronchiectasis was excluded in all patients by bilateral bronchography. Clinical and histopathologic evidence of the Sjörgen autoimmune exocrinopathy was documented in five of the patients, and the sixth patient had lymphoplasmocytic infiltrates of the labial glands without obstruction of the lumen or destruction. By pulmonary function tests and histopathologic examination of four open lung biopsies, the airway disease was found to be located predominantly in the peripheral airways of the lung. On each biopsy, the lesions were in different stages of activity, but on all specimens there was a definite predilection for selective bronchiolar injury. Early stage lesions were characterized by mononuclear cell infiltrates of the peribronchiolar tissue which led to deformation of airway lumen, focal mucosal extension and ulceration. Subsequently, the inflammatory reaction was replaced by fibroblastic proliferation, and in the end stage of the disease, there was complete obliteration of many bronchioles by collagenized fibroblastic tissue. From regression analyses of serial pulmonary function tests of these patients, it was concluded that (1) the airway disease in our patients who did not smoke progressed inevitably but not uniformly and (2) deterioration of pulmonary functions was more rapid in our patients than it was in the cigarette smokers who had chronic obstructive lung disease. This study also documents major dysfunctions of the chest wall mechanics which appear to contribute to the restriction of lung volumes in some rheumatoid patients.