Body-cavity-based lymphoma (BCBL) is a recently described subtype of human non-Hodgkin's lymphoma characterized by the localization of neoplastic cells exclusively in the body cavities. BCBL is found most commonly in AIDS patients, and is known to be highly associated with Kaposi's sarcoma-associated herpes virus (KSHV). We describe here a case of BCBL that occurred in a 101-year-old man. He was successively treated with etoposide, but died 8 months after the diagnosis of BCBL. No lymphoma masses were noted at pre- and postmortem examinations. KSHV was demonstrated in large numbers in the neoplastic cells using semiquantitative PCR analysis. Although there have been four brief reports of HIV negative BCBL, the present case is the first for which the detailed clinical course and response to chemotherapy have been recorded.