Chronic tuberculous pyothrax and the development of non-Hodgkin's lymphoma (NHL) on the chest wall are believed to be closely related. We encountered three patients with NHL involving the chest wall in whom the tumor may have had a different origin Patient 1: A 65-year-old man with a history of pulmonary tuberculosis and right-sided pyothrax at the age of 28 years was found to have a tumor on the right sided of the chest wall, and NHL was diagnosed. Patient 2: A 65-year old woman with a history of right-sided tuberculous pyothrax at the age of 2 years had a left-sided chest-wall tumor, and NHL was diagnosed. Patient 3: A 78-year-old man with a history of tuberclous pleuritis on the left side at the age of 77 years was found to have a left-sided chest-wall tumor, and NHL was diagnosed. In patients 1 and 2, the Epstein-Barr virus was found in tissue specimens by in situ hybridization. These findings suggest that chronic tuberculous pyothrax and the development of NHL on the chest wall were not closely related in these patients, and that the Epstein-Barr virus may play an important role in the development of NHL on the chest wall after tuberculous pyothrax.