This book provides an up to date definition of Bacterin. It broadens its concept to cover the preventive and therapeutic versions of bacterins. Currently, bacterin; Approved bacterins, experimental bacterins with details on autgenous and stealth bacterins, bacterins allied biologics, the probiotics as well as subunit and genetic bacterin. The text covers five parts, seven sections and 27 letters. Each letter consists of single idea within the immunobiology of bacterin of each group. The text of each letter include four subheads as synopsis, theme, conclusion and references. Issue for the use of autogenous bacterin in human welfare are presented. The book is intended to be of use for academician public health professionals and freshmen bacterin workers.