We previously have reported on an experimental athymic mouse model in which regression of human Burkitt's lymphoma is induced by either coinjection with or intratumor inoculation of Epstein-Barr virus (EBV)-immortalized human B cells. In the current study, we were interested in determining whether the powerful antitumor effects of EBV-immortalized B cells could be effective against a variety of human tumors grown in athymic mice, including acute lymphocytic leukemia, malignant melanoma, acute promyelocytic leukemia, neuroblastoma, lung carcinoma, colon adenocarcinoma, Wilms tumor, Hodgkin's lymphoma, rhabdomyosarcoma and breast adenocarcinoma. We report here the results of experiments in nude mice that demonstrated the potent antitumor effect of EBV-immortalized B cells against human tumors derived from a variety of different tissues.