The clinical goal of tumour immunotherapy is to provide either active or passive immunity against malignancies by harnessing the immune system to target tumours. Although vaccination is an effective strategy to prevent infectious disease, it is less effective in the therapeutic setting for cancer treatment, which might be related to the low immunogenicity of tumour antigens and the reduced immunocompetence of cancer patients. Recent advances in technology have led to the development of passive immunotherapy approaches that utilize the unique specificity of antibodies and T cell receptors to target selected antigens on tumour cells. These approaches are likely to benefit patients and alter the way that clinicians treat malignant disease. In this article we review recent advances in the immunotherapy of cancer, focusing on new strategies to enhance the efficacy of passive immunotherapy with monoclonal antibodies and antigen-specific T cells.