We have conducted a prospective comparison of 155 rheumatoid patients and 95 control subjects. Both groups were selected without regard to respiratory status, but were comparable in age, sex and smoking experience. The prevalence of respiratory symptoms, of past respiratory illnesses and of pulmonary function findings of airway obstruction was similar in both groups. However, the rheumatoids showed an increased frequency of chest crackles and abnormal chest radiographs, and had pulmonary function changes suggestive of a restrictive ventilatory defect. These pulmonary abnormalities were associated with smoking, the presence of nonpulmonary extraarticular features, the level of rheumatoid disease activity and treatment with oral corticosteroid or gold.