We report a case of pleural malignant lymphoma associated with chronic tuberculous pyothorax. A 67-year-old male was hospitalized because of left lateral chest swelling and pain. He had suffered from pulmonary tuberculosis at the age of six and tuberculous pleurisy at the age of 24. We made a histologic diagnosis of malignant lymphoma diffuse large B-cell type. He was medicated THP-COP (THP, CY, VCR, PSL) therapy and his chest pain and swelling has improved gradually. From the view point of molecular biology, we detected Epstein-Barr virus (EBV) infection in the pyothorax wall. In conclusion, we should be more careful about medical examination in patients with EBV positive tuberculous pyothorax considering the complication of malignant lymphoma.