The chitin, chitosan and their derivatives are found increasing uses day by day with more than 200 applications that include cosmetics, agriculture, food, biomedical, textile etc. This book provide an avenue for the wise utilization of bivalve shell which is so far used only for ornamental purpose apart from being a raw material for lime production, towards additional uses of bivalve shell for production of chitosan and its derivatives, as it consists of chitin. In medical science, it has been reported that chitosan and its derivatives play important role in drug release control, oral hygiene, periodontal use, antitumour, antiulcer, anticoagulant, hemostasis, wound healing and dressing, etc. Now-a-days, researchers are interested in finding natural antioxidants like chitosan and its derivatives since they protect the human body from free radicals and also retarding the progress of many chronic diseases. Further, the antioxidant activity of chitosan and its derivatives has attracted the most attention due to their non-toxic nature and natural abundance.It can also throw light on its utilization in the in the pharmaceutical and neutraceutical industries.