Lectins are an important group of proteins, which bind to carbohydrates and can agglutinate cells or precipitate polysaccharides and glycoproteins. These agglutinating and precipitating properties are very similar to those of antibodies, and hence many of the methods used in lectin research are based on immunochemical techniques. Lectins are however not of immune origin, and are found in almost all organisms, including plants and micro-organisms. Current interest in lectins derives particularly from their usefulness in detecting and studying carbohydrates in solution and on cell surfaces. Studies of lectin-carbohydrate interactions are providing information on the precise molecular details of the interactions between proteins and carbohydrates in general. Lectins also serve as valuable tools in biological and medical research, in areas as diverse as separation and characterization of glycoproteins and glycopeptides, typing of bacteria and fractionation of lymphocytes and of bone marrow cells. Their biological role is uncertain but is generally believed to be primarily as recognition determinants in mirco-organisms, plants and animals. The purpose of the book is to give an accessible overview of the properties of lectins, their possible roles and their applications in biology and biomedical research in biochemistry and cell biology. This book should be of interest to biochemists, biologists, microbiologists, pathologists, histologists, cancer researchers, immunologists and haematologists.