Background. Measurement of adenosine deaminase (ADA) is useful to diagnose tuberculous pleurisy, but some cases have low pleural effusion ADA levels. Case. A 93-year-old woman had undergone chemotherapy for malignant lymphoma of the small intestine, which did not relapse after chemotherapy. She was admitted to our hospital with right chest pain and dyspnea caused by a right pleural effusion. After admission, thoracentesis was performed, and the pleural effusion was found to be exudative and lymphocyte-dominant, with a low ADA level and no malignancy. Thoracoscopy was then performed under local anesthesia, and many yellowish-white, small nodules were seen on the parietal and visceral pleura. Microscopic examination of the pleural specimens showed epithelioid granuloma with caseous necrosis, yielding a diagnosis of tuberculous pleurisy. Her symptoms improved and the right pleural effusion decreased with INH, RFP, and EB treatment. Conclusion. Even in elderly patients, thoracoscopy under local anesthesia can be safe and useful for diagnosing tuberculous pleurisy.