The discovery that immune T-cells recognize intracellularly processed peptides associated with major histocompatibility locus molecules has revolutionized the cancer vaccine field by providing new reagents for the generation of immune responses against cancer. The cloning of tumor antigen genes has proceeded most rapidly in melanoma because of the ease with which melanoma-specific T-cells can be propagated in vitro. The cloning and identification of tumor regression antigens and data from the initial clinical trials with peptides vaccines derived from those antigens are presented here.