This review describes clear parameters for designating the correct use of the term Tumor Rejection Antigen [TRA] to define the role of tumor cell constituents which activate adaptive anti-tumor immune reactions in the cancer-bearing host. This is important, especially in defining immunogens which activate the patient's cytotoxic T-cells that are important to immunotherapeutic applications in human cancer treatment. The focus of the review is to correctly delineate the immunogenic properties of 37 kDa oncofetal antigen [OFA], one of only a few true TRAs expressed on human and experimental rodent cancers. The purpose of this review is to provide a background for publication reviewers, journal and text editors, and scientists reporting on TRAs to avoid creating further confusion that has proliferated in the cancer literature to imply traits of so-called tumor-associated antigens that do not qualify as TRAs.