Active specific immunotherapy holds great potential in the search for new therapeutic approaches for patients with cancer. Much preclinical and clinical evidence has shown that the immune system can be polarised against malignant cells by several vaccination strategies. Although no anticancer vaccine can be recommended outside clinical trials at present, tumour response and immunological findings in animals and humans should prompt researchers to investigate further the potential of this biotherapy. We summarise strategies for cancer vaccines so far implemented in the clinical setting, report the results of more than 200 clinical trials published over the past two decades, and discuss insights into preclinical tumour immunology that might aid the design of the next generation of cancer vaccines.