The study of carbohydrates in biology is one of the longest-established aspects of the subject. In consequence, it is treated in most text- books of biology and biochemistry at least at an elementary level. However, certain areas of carbohydrate biochemistry have expanded rapidly over the past few years as a result of intense research activity. Such advances make this an opportune time to draw together the newer ideas of carbohydrate functions and to present them within a framework of established knowledge. This book describes the role of carbohydrates in biology at a level which is suitable for undergraduate students in biochemistry, biology and the medical sciences. The subject is treated to the final-year level although, inevitably, advanced students will wish to expand their knowledge of particular topics by use of the reading list provided as an appendix. Two areas are particularly emphasized. The first is the metabolic reactions of carbohydrates and the functions of such reactions in the organism. Here the regulation of metabolism in response to different physiological requirements is stressed, and concepts of compartmentation and transport are explored. The second area is concerned with the metabolism and functions of carbohydrate polymers. Here there has been a rapid expansion of research, particularly into the role of specific interactions of carbohydrates which occur, for example, at cell surfaces.