To test whether antibodies directed to TCR affect T cell tumor growth in vivo, mice were inoculated intravenously with C6VL tumor cells expressing V beta 6 TCR and then treated intraperitoneally with mAb specific for V beta 6 TCR. Administration of anti-V beta 6 antibody prolonged survival of mice bearing V beta 6-expressing tumor cells and it led to the induction of host immunity to the tumor cells in surviving animals. This treatment eliminated not only tumor cells bearing V beta 6 TCR but also normal host T cells expressing V beta 6 T cells receptors. However, the lack of V beta 6-expressing T cells in such treated mice did not result in generalized immune disfunction. These data demonstrate the utility of anti-TCR V segment antibody in the treatment of T cell tumors. Most importantly, since the number of V genes for the T cell antigen receptor is limited, both in man and in mouse, it should be possible to establish a panel of mAbs directed to each V gene product and use such antibodies in the treatment of T cell neoplasms.