While vaccines are primarily thought of in terms of their use for prevention of infectious diseases, they can potentially be used to prevent or treat cancer. This manuscript explores the rationale for vaccines and immunotherapies for cancer from both the scientific and the global needs perspectives. Pathogens that are aetiologic agents of certain cancers provide perhaps the most obvious successful examples of the prophylactic utility of vaccines (such as the hepatitis B vaccine) to prevent not just the infectious disease (hepatitis), but the potential subsequent cancer (hepatocellular carcinoma). The use of monoclonal antibodies illustrates the effectiveness of the immune system for cancer therapy. In addition, the increased understanding of the role and mechanisms of the immune system in the processes of immune surveillance, as well as of its failure during immunosuppression, have yielded better insights into how to design cancer vaccines and immunotherapies. Examples of targets for cancer vaccines will be discussed, as will the challenges and few successes in this arena.