22 patients with primary Sjogren's syndrome were prospectively studied for respiratory system involvement with clinical, roentgenological and functional parameters. 12 patients (55%) had respiratory manifestations. In 10/12 (83%), respiratory symptoms occurred before or concomitantly with the classical symptoms of Sjogren's syndrome. There were two distinct forms of respiratory involvement: xerotrachea, manifested by dry cough without other symptoms and negative roentgenological and functional evaluation and diffuse interstitial lung disease manifested by dyspnea with or without dry cough with bibasilar rales, compatible chest roentgenogram, restrictive pattern in spirometry and/or hypoxemia. Xerotrachea was more common in patients with glandular form of Sjogren's syndrome (3/10) and diffuse interstitial lung disease in patients with extraglandular form (6/12). None of the 22 patients had pleurisy or other forms of respiratory involvement. Antibodies to Ro (SSA) and La (SSB) antigens were more common in patients with the extraglandular form of the syndrome but did not correlate with diffuse interstitial lung disease.