In this study we tried to value the frequency and the characteristics of the physiological abnormalities affecting the lungs in Sjögren's syndrome (SS). We studied 18 female nonsmokers (average age 53 years). The diagnosis has been made on the presence of at least two of the following abnormalities: keratoconjunctivitis sicca (Schirmer's test), xerostomia (scanning of the salivary glands, lip biopsy) and collagen vascular disease. We made the following tests: clinical examination, chest roentgenogram, spirometry, TGV, RAW and SAW valuation, study of the flow-volume curves, diffusion capacity test, bronchoalveolar lavage, bronchial biopsy. The physiological results have demonstrated the presence of a restrictive syndrome affecting above all the small airways (MEF25-32.7%) and a decrease of the diffusion capacity (DLCO-25%). There is, moreover, a constant lymphocytic infiltration of the bronchial mucosa and of the lung's interstitium. In conclusion the pulmonary involvement in SS seems to be constant, unpredictable and of remarkable clinical-physiological importance.