The synthesis of hybrid organic-inorganic nanocomposite materials containing biopolymers by the sol-gel processing is often faced with severe difficulties owing to their poor compatibility with the common precursors. The problem was solved when tetrakis(2-hydroxyethyl) orthosilicate (THEOS) was recently suggested for the preparation of sol-gel derived nanocomposites. This article summarizes recent data on novel types of hybrid polysaccharide-silica nanocomposite materials fabricated with the help of THEOS. Their formation, properties and structure as well as features and possible mechanism for the sol-gel processes are considered. It is demonstrated that the novel approach is particularly suitable in situations where others are unsatisfactory. This includes systems of which supramolecular organization or phase state is sensitive to the pH of solutions, temperature and addition of organic solvents. One example of a successful application is the immobilization of labile enzymes. The biocompatibility of THEOS allows their activity to be retained, thereby enhancing long-term and thermal stabilities.