AIM: To identify the human leucocyte antigen A2 (HLA-A2) restricted cytotoxic T lymphocyte (CTL) epitopes from tumor antigen PIWIL2.METHODS:RT-PCR and Western blot was used to determine the expres-sion of PIWIL2 in cancer cell lines MCF-7, SW480 and HT-29.HLA-A2 epitopes from PIWIL2 protein were predicted by the software of BIMAS, RankPep, NetMHC, NetCTL1.2 and IEDB.The peptides were synthesized by standard solid-phase methods.The binding affinity of the peptides to HLA-A2 molecules was evaluated by T2 cells binding assay.ELISPOT as-say was used to investigate the levels of IFN-γ.The cytotoxicity assay in vitro was also used to determine the ability of indu-cing T cell response by the peptides.RESULTS:The expression of PIWIL2 was observed in MCF-7, SW480 and HT-29. The candidate peptide P485, P493 and P965 showed moderate affinity toward HLA-A2 molecule.ELISPOT assay showed P485 and P965 induced CTLs of IFN-γrelease form CTLs.The CTLs induced by P485 and P965 lysed the MCF-7 cells. CONCLUSION:The peptides P485 and P965 are excellent HLA-A2 restricted cytotoxic T lymphocyte epitopes from the tumor antigen PIWIL2, which could serve as new candidates towards antitumor peptide vaccines.