Pleuropulmonary rheumatoid nodules were diagnosed histologically in six patients of whom five were known to have rheumatoid arthritis; the pulmonary lesion preceded the development of arthritis in the sixth patient. Pulmonary lesions are commonly found in patients with rheumatoid arthritis. These lesions are either non-specific (effusions, pleurisy, fibrosis, arteritis and obliterative bronchiolitis) or the specific necrobiotic nodules that constitute Caplan's syndrome in association with pneumoconiosis. The necrobiotic nodules are usually pleural or subpleural and rarely occur in the bronchial tree. Pulmonary necrobiotic nodules can appear before, coincident with, or after the onset of arthritis. It is essential to distinguish these lesions from infections or neoplasia.