Despite major advances in standard cancer treatment, many patients relapse or progress after a period of time. Cancer immunotherapy is being extensively investigated to provide a treatment with less side effects impacting on quality of life as compared to classical therapies. Dendritic cells (DC) are professional antigen-capturing and -presenting cells which are capable in balancing the immune system between immune stimulation and tolerance. We explored the use of dendritic cells for the development of immunotherapy in leukemia patients to stimulate and enhance T cell-mediated immune responses. Wilms’ tumor protein (WT1), overexpressed in many cancer types, was chosen as target antigen. This book describes the way a dendritic cell vaccine is produced: from the early proof of concept experiments to the final generation of a clinical applicable vaccine of WT1-loaded DC in a stage I/II trial with 10 acute myeloid leukemia (AML) patients in remission. The data obtained in this trial and data from other trials using WT1 as target antigen are compared. Altogether this book is valuable for everybody who likes to know more about immunotherapy and dendritic cells in the treatment of AML.