The melanoma antigen coded by the MAGE-1 gene was the first tumor antigen described in human cancer. Genetic, biochemical, and "candidate peptide" strategies have been used to identify antigenic peptides presented to T-cells by class I major histocompatibility complex antigens. Antigens have now been characterized in a wide variety of tumor types. Five categories have been described based on expression profile. These antigens are detailed in this review. Among the tumor antigens produced as a result of intratumoral mutations, some are of special interest because of their potentially oncogenic effects. These new data can be expected to lead to the development of novel anticancer treatments based on specific immunotherapy. Pilot clinical studies are ongoing.