A 46-year-old woman with a 2-year history of xerostomia, who had had an episode of suspected Sjögren's syndrome in 1995, was admitted to our hospital because of a dry cough. Chest radiography on admission showed ground-glass infiltrates and reticular shadows in both lower lung fields. Primary Sjögren's syndrome was diagnosed by lip biopsy. Video-assisted thoracoscopic lung biopsies revealed the co-existence of interstitial pneumonia with the BOOP pattern and follicular bronchiolitis. Treatment with oral prednisolone improved the symptoms, and reduced the abnormal chest shadows. This was an interesting case of the BOOP pattern in a lung lesion associated with primary Sjögren's syndrome.