W e have come a long way since the identification of the first human tumor antigen recognized by autologous CTL. This report provides a brief appraisal of these antigens and their potential for cancer immunotherapy. Our comments will be restricted to nonviral antigens. The initial work carried out on mouse tumors revealed two possible mechanisms for generating new antigens that might be suflficiendy tumor-specific to be of relevance to immunotherapy. The first mechanism involved a point mutation, and the second involved the transcriptional activation ofa gene not expressed in normal tissues (1-3). Subsequent work on mouse tumors provided two interesting examples of tumor antigens resulting from point mutations (4, 5).