Primary effusion lymphoma (PEL, or body-cavity-based lymphoma [BCBL]) is a new subtype of non-Hodgkin's lymphoma in which tumor cells locate in the body cavity exclusively. PEL/BCBL is widely accepted as one of the neoplastic complications of AIDS, associated mostly with human herpesvirus 8 (HHV-8/Kaposi's sarcoma-associated herpesvirus [KSHV]) and Epstein-Barr virus (EBV). We established and characterized a PEL cell line named TY-1 from a 47-year-old patient with AIDS. TY-1 exhibits indeterminate immunophenotype, expressing CD45 and CD30 cell surface antigens but not expressing B- or T-cell markers. Cytogenetic analysis revealed the representative karyotype of 50,XYq-,+7,+8,+11,+15. Southern blot analysis demonstrated HHV-8 and EBV genomes in the original tumor cells obtained from the pericardial effusion, while HHV-8 but not EBV was detected in TY-1 using PCR or Southern blot analysis. Tetradecanylphorbol acetate treatment induced some TY-1 cells to proceed to the reproductive phase. This cell line may be an useful tool for research on PEL and HHV-8.