A review of 343 patients with classic Sjogren's syndrome seen at the Mayo Clinic from 1967 through 1974 revealed pulmonary involvement in 31 patients (9 percent). Cough dyspnea, recurrent pneumonitis, and pleuritic pain were the primary complaints. Chest roentgenographic features included diffuse interstitial patterns, diffuse alveolar patterns, and pleural effusions. Laboratory studies revealed hypergammaglobulinemia in 16 of 22 patients tested, and 23 of the 31 patients had positive tests for anti-nuclear antibody, rheumatoid factor, or lupus erythematosus cells. Pulmonary function tests showed a restrictive ventilatory impairment or low diffusion capacity (or both in all 18 patients studied. Pathologic diagnosis included the full range of pulmonary lesions described in Sjogren's syndrome syndrome, ie, lymphocytic interstitial pneumonitis, pseudolymphoma, malignant lymphoma, diffuse interstitial pulmonary fibrosis, and bronchopneumonia. The clinical pulmonary diagnosis included diffuse interstitial fibrosis, recurrent pneumonitis, pleural effusions, and suspected lymphoma or pseudolymphoma. We conclude that pulmonary lesions occur in Sjogren's syndrome more frequently than previously reported.