Tumor immunology and immunotherapy attempt to use the exquisite specificity and lytic capability of the immune system to treat malignant disease with a minimum of damage to normal tissue. Increasing knowledge of the identity of tumor antigens should point the way to effective therapeutic vaccines or more specific immunotherapeutic strategies. Tumors, however, have evolved mechanisms to inactivate cytolytic T-cells and other immune responses targeting tumor antigens. The current goal of immunotherapy research is to use contemporary advances in cellular and molecular immunology to develop strategies to overcome the disabling effects of the tumor microenvironment on the immune system attack against tumor antigen targets. This review will summarize our current knowledge of the spectrum of tumor antigen targets available for immune recognition in cancer, the obstacles to tumor immunotherapy, the use of adoptive immunotherapy to overcome some of these obstacles, the use of monoclonal antibodies to target tumor antigens for immunotherapy, and finally the potential use of heat shock proteins as targets for cancer immunotherapy.