The subject of matter of this book presents an interface between radiation biology and medicine and concerns knowledge and experiences obtained mostly in the last two decades in the field. The data are based on the chemical and biological effects induced by high-energy radiation in aqueous systems of vitamins and cytostatica as well as mixtures of both.The reducing and oxidising free radicals in the human organism are governing the various biological processes. They can also be produced by ionising radiation in each desired kind, a concentration in aqueous systems. Based on this fact, it is possible to perform appropriate studies in order to gain a deeper insight in the very complicated and fast biological processes. The purpose of this is to present, for the first time in a book, a critical scientific overview of the published radiation-induced antitumour-effects of vitamins and related substance as an anti-tumour agent.