Twenty-seven patients (25 women, 2 men) with primary Sjögren's syndrome, previously reported to have reduced pulmonary diffusing capacities were reexamined in a 7-year follow-up in order to evaluate longitudinal alterations in pulmonary function. Primary Sjögren's syndrome was diagnosed according to the Copenhagen criteria. The present examination revealed normal and unchanged values for vital capacity, forced expiratory volume in 1 s, maximal expiratory flow at 50% of expired vital capacity (MEF50), and diffusing capacity per liter alveolar volume. Total diffusing capacity (P less than 0.01) and MEF75 (P less than 0.05), were, however, significantly reduced compared with the predicted values, indicating pulmonary involvement primarily affecting the small airways. The longitudinal examination, furthermore, showed increasing values for total diffusing capacity (P less than 0.02), diffusing capacity per liter alveolar volume (P less than 0.001), and MEF75 (P less than 0.02), suggesting an improvement in lung status in the course of time. No correlation was found between MEF75 and diffusing capacities, nor between alterations in pulmonary function and complaints of dyspnoea, tiredness, cough, expectoration, tobacco smoking, or medical treatment with bromhexine, glucocorticosteroids, essential fatty acids, or nonsteroid antiinflammatory drugs.