The field of peptide based cancer vaccines has evolved tremendously in the last decade of this century. The exploration on how to apply the peptide knowledge for vaccination purposes began when it was demonstrated that these peptides after being mixed into adjuvants actually induced T cell responses that could prevent virus infections and tumor growth in experimental animal models. The results of animal models are currently translated into clinical applications with all their associated difficulties and heterogeneity. Initial promising data do appear, warranting further research in this area. This book pays tribute to key researchers in the field.