Among the various natural polymer-based gene delivery vectors, chitosan is the most prominent. As a biocompatible, biodegradable, nontoxic and easily modifiable material, chitosan has been widely researched for a variety of biomedical applications such as wound healing, drug/gene delivery systems, implant coatings and tissue engineering/regeneration.Chitosan was first described as a delivery system for plasmids by Mumper's group in 1995. The role of chitosan in gene delivery was supported by its ability to protonate in acidic conditions and to form complexes with anionic DNA by electrostatic interactions. The biodegradable cationic polymer chitosan is capable of forming small and stable toroidal complexes with plasmid DNA and provide protection against DNase that is comparable to PEI. The objective of this book is to integrate the concepts related to chitosan and its derivative-based drug/gene delivery carriers. For example, the success of the gene delivery system mainly depends upon the uptake by the cells, unpacking behaviour of pDNA/siRNA from the vector and its intracellular trafficking. Such concepts are introduced and discussed, in addition to the various applications of chitosan as a drug delivery system in wound healing, tissue engineering and in gene delivery. This book is an excellent resource for the academic faculty, graduate students and professionals interested in chitosan-based drug/gene technologies.