Synopsis Bacteria are important group of microorganisms and their role in the service of mankind has been recognized well, apart from their association in causation of serious diseases of human being, plants and animals. Phytobacteriology is the new branch of Bacteriology and is still in its infancy stage. Dates back that in the end of twentieth century, the bacteria were recognized as the cause of plant diseases. Since then, the rapid progress has been made in the study of phytopathogenic bacteria, which are responsible for causing great losses to cereals, vegetables, fruits and ornamenta plants. Considering the importance of these microscopic organisms, recently a separate course of Phytobacteriology has been introduced in syllabus of SAUs and there is not much literature available for the students. In order to fulfil the requirements of syllabi of postgraduate teaching in Phytobacteriology of SAUs and Botany of general Universities, this complication has been brought out dealing with 12 chapters on different aspects of bacteria. Introductory Phytobacteriology is intended primarily for the students of SAUs and others who are interested in bacteriology may find the book useful as a background of knowledge, which will make it possible to appreciate the part bacteria play in their lives. There is at present a dearth of text books on bacteriology for the students of agriculture and this had inspired the authors to improve upon their class lectures by seeking information from many experts in their respective field of studies and present it as a text book based on ICAR revised course curricula. Efforts have been made to introduce the subject to the beginners for clear understanding of the importance, morphology, classification, nutrition, reproduction in bacteria and important diseases of plants caused by them. The procedure and techniques including isolation, inoculation and staining have also been described for proper identification and characterization of bacteria. Definition and terminology used in the study of bacteria have also been explained in a precise manner. The outcome of this book is the result of the ICAR sponsored Ad-hoc scheme on multimedia module preparation on Phytobacteriology. The recent classification of bacteria, as given in Bergey’s Manual of Systematic Bacterilogy has been incorporated in this book. We are hopeful that this compilation will be useful to the students and teachers of Agricultural Universities and those interested in the study of phytopathogenic bacteria and also as a part of course in Microbiology and Botany of general Universities.