The key strategy for the advancement of gene therapy is the development of an efficient targeted gene delivery system into cells. The targeted gene delivery system is especially important in non-viral gene transfer which shows the relatively low transfection efficiency. It also opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been considered to be a good candidate for gene delivery system, since it is already known as a biocompatible, biodegradable, and low toxic material with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this study, we focused on the chemical modification of chitosan for enhancement of cell specificity and transfection efficiency. Also, the potential of clinical application was investigated.