Despite recent advances in the treatment of colorectal cancer, the overall survival rate for those patients with advanced locoregional disease remains less than 50%. Although adjuvant systemic chemotherapy has improved survival of these patients, more effective therapies are needed. Immunotherapy is an approach that could have a particular role in the adjuvant therapy of colorectal cancer. There is now convincing evidence that the immune system can specifically recognize and destroy malignant cells. Although both antibody- and T-cell-mediated anti-tumor responses have been documented, the cellular immune response with its direct cytotoxic mechanisms is felt to be the principal anti-tumor arm of the immune system. Analysis of the T cells that recognize tumors has led to the identification and characterization of many tumor-associated antigens including several colorectal antigens. Current approaches to developing a vaccine for colorectal cancer use our expanded understanding of these tumor-associated antigens and the conditions that allow development of an effective cellular immune response to them.