For some time immunotherapy has been heralded as a breakthrough approach for cancer treatment. Although the potential of this strategy remains solid, the approach needs considerable refinement. Whilst some programmes are looking to increase the understanding of molecular and cellular mechanisms underlying the stimulation of antitumor immunity, others are trying to find the most appropriate clinical setting that will reveal the role of the immune system in combating cancer. Among the most important discoveries have been tumor-specific antigens. This thematic volume highlights some key issues and discusses where they may move forward. It has been put together by two leading cancer immunotherapists from two eminent institutions that focus on cancer research.