The immune system is a complex arrangement of cellular interactions that preserve the integrity of a organism by elimination of all elements judged dangerous. However, the development of tumours in immunocompetent patients suggests the existence of an imbalance that favours tumour cells against the immune response. What are the different possibilities for reversing this process to drive an efficient antitumour response? We discuss, focusing on the haematological features, classic immunity (ie, antigen-specific and HLA-restricted immunity). We address the central issues of tumour antigen presentation and recognition and their possible clinical use. Last, we discuss non-HLA-restricted immunity, which does not require the recognition of specific antigens and relies on particular cell populations such as natural killer cells.