Recently, numerous scientific articles related to water soluble chitosan (WSC) have been released. Since the solubility of chitosan is restricted to acidic media, and there is an increasing demand against to the derivative of the chitosan polymer, which is mainly to obtain a material both having solubility in aqueous media and also being chitosan property. One of the benefits of synthesis of water soluble chitosan is to obtain a water soluble polymer is easily miscible with a variety of compounds in aqueous solutions. In this review, water soluble chitosan derivatives are principally examined in terms of their biological and other applications. Biological activities of WSC derivatives are analyzed in the sense of antioxidant, antimicrobial and anticancer activity, respectively. Thereby, the collected data may be useful to compare novel synthesized water soluble chitosan derivatives with alternative structures.