1. Introduction 2. Distribution and role of hemicelluloses in the structure of the plant cell wall 3. Biosynthesis of hemicelluloses 4. Sources 4. Biomass biorefining as a possibility to recover hemicelluloses 5. Characterization of hemicelluloses: chemical composition, structure and properties 6. Applications: furfural and furan resins, hydrolysis and fermentation (ethanol and yeasts), paper manufacture (additives, packaging), medicinal and pharmaceutical as enzymes and drugs, a.s.o.