Abstract The CD8αα homodimer as well as the NK cell receptor-protein 1 (NKR-P1) have been implicated to be preferentially expressed by T cells that develop extrathymically. We have earlier shown that intraperitoneal administration of radiated syngeneic W439 lymphoma cells in rat induces tumor-specific cytotoxic T cells (CTL) expressing the TCRαβ receptor as well as the TCRγδ receptor. In the present study we have addressed the expression of CD8αα/αβ and NKR-P1 on these CTL and their correlation to cytotoxicity activity against the W439 tumor. The induced CD8 +T cells differentiated to effective cytotoxic cells regardless of the CD8 composition. NKR-P1 +T cells expressing CD8 were found in the peritoneal cavity of untreated rats and this cell population was markedly increased upon lymphoma immunization. Both TCRαβ +cells and TCRγδ +cells expressing NKR-P1 showed high cytotoxicity against the tumor. TCRγδ +NKR-P1 −cells were also cytotoxic against the tumor, while TCRαβ +NKR-P1 −cells showed no cytotoxicity. NKR-P1 +T cells (TCRαβ +and TCRγδ +) were not cytotoxic against NK sensitive targets, which contradicts earlier data implicating a correlation between the expression of NKR-P1 and MHC-unrestricted cytotoxicity. In conclusion, TCRαβ +anti-lymphoma CTL express high levels of LFA-1 and NKR-P1, while the TCRγδ +CTL are not dependant on NKR-P1. These results suggest that NKR-P1 has a different function within the TCRαβ +CTL than within the TCRγδ +CTL in the recognition process of these lymphoma cells.