This monograph summarizes scientific achievements in the field of polysaccharide chemistry performed in the last decade. For the first time, the particular features of polysaccharide structure, physical-chemical properties and biochemical transformations in their interrelations are considered as well as the questions of polysaccharide modification along the whole hierarchical chain, including starch mono-, di-, oligo- and polysaccharides, chitin, chitozan and cellulose. Polysaccharide interactions with diverse solvents and low-molecular, macrocyclic and high-molecular substances in solutions are scrutinized. Several aspects of mechanical-chemical modification of polysaccharides in solid state and in gel are observed. Modern concepts of enzyme degradation of polysaccharides and technologies of natural polymers processing are analyzed. The book is intended for wide range of readers: students, post graduates, engineers and scientists engaged in polymer chemistry, organic and physical chemistry.