A cultured glioma cell line, SR-B10.A, which was derived from a brain tumor induced in an adult female B10.A mouse by Rous sarcoma virus (RSV), has been established. The morphological appearance of the tumor produced by s.c. inoculating SR-B10.A cells was analogous to an astrocytoma of human glioma. Glial fibrillary acidic protein as well as S-100 protein was positive in these SR-B10.A tumor cells. A population doubling time of the cultured cells was 18.5 hours. Chromosomal analysis revealed a defect in one of the sex chromosomes. Integration of RSV genome was proven to be positive in SR-B10.A cells. It was possible to generate cytotoxic effector cells in the syngeneic B10.A mouse against SR-B10.A. The tumor-bearing syngeneic hosts harbored a suppressor activity in the splenocytes. Although recombinant human tumor necrosis factor (rH-TNF) had no growth inhibitory effect on the SR-B10.A cells in vitro, the s.c. implanted and growing tumor regressed when rH-TNF was administered intratumorally several times. In addition, this anti-tumor effect was completely abrogated when the host mice were treated with wholebody x-ray irradiation prior to the tumor cells inoculation. In contrast, neither rH-TNF (i.v.) nor cyclophosphamide (i.p.) induced the regression of SR-B10.A, indicating that efficacy of the locally administered rH-TNF is dependent on the host immune mechanism. These results suggest that SR-B10.A is a potentially useful tumor model in evaluating efficacy of immunomodulators.