The concept of cancer immune surveillance dates back decades and is based on the hypothesis that the immune system can suppress the development or progression of spontaneous malignancies. Immunotherapy strategies include antitumor monoclonal antibodies, cancer vaccines, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies that either costimulate immune cells or block immune inhibitory pathways. Sipuleucel-T is the first anticancer vaccine that improved overall survival in a randomized clinical study in patients with metastatic castration-resistant prostate cancer. Similarly, ipilimumab, a monoclonal antibody blocking cytotoxic T-lymphocyte antigen 4 (CTLA-4), showed an overall survival benefit and durable tumor responses in pretreated and previously untreated patients with metastatic melanoma. In Switzerland, ipilimumab is approved for second line treatment in metastatic melanoma. These recent positive results of clinical trials with novel immunoactive drugs raised expectations that immunotherapy will play a crucial role in the anticancer treatment of the next decade.