Diverse alterations of glycosylation occur in diseases such as cancer, metastasis, leukemia, inflammatory and other diseases. The glycosylation abnormalities found in disease are the result of complex rearrangements of the oligosaccharide assembly by glycosyltransferases. This volume reviews several mechanisms that may underly the extremely complex alterations in disease. Disease specific glycosylation may contribute to the disease process by altering cellular functions, or may be exploited therapeutically. Specific therapy may be aimed at correcting glycosylation abnormalities based on knowledge of the mechanisms leading to the disease phenotype and the three-dimensional interactions between carbohydrates and carbohydrate-binding molecules.