Immunotherapy induces a response against cancer by activating the immune system. Examples are therapies with checkpoint inhibitors, oncolytic viruses and chimeric antigen receptor T-cells (CAR T-cells). These therapies have, due to their rapid development, found their way to daily practice. For some patients with metastatic disease immunotherapy has led to significant long-term survival. Currently, there is a shift in the treatment with checkpoint inhibitors towards the (neo)adjuvant setting. Treatments with CAR T-cells seem particularly effective in haematological malignancies. Oncolytic viruses are used in the treatment for melanoma, but presently only on a limited scale. Only a limited number of patients benefit from immunotherapy. There remain many challenges for the future, most importantly the optimal use of treatment, recognition and treatment of side effects, determining the optimal duration of treatment and the increasing healthcare costs.