The body-cavity-based lymphoma cell line BCBL-1, which is infected with Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8, was injected alone or with human peripheral blood mononuclear cells into SCID mice. Immunoblastic lymphomas developed at or near the site of injection. The lymphomas appeared to derive exclusively from the injected BCBL-1 cells and not from the injected human PBMC. The tumors elicited a marked murine angiogenic response, but known angiogenic cytokines were not detected in BCBL-1 cells. Transfer of BCBL-1 cells to SCID mice may represent an in vivo model for the study of KSHV/HHV8-stimulated angiogenesis.