Carbohydrates play a wide range of important roles in the body and, despite the challenges posed by glycobiology, are now tempting targets for drug developers. Although several genomes have been sequenced and many protein structures solved, there has been relatively little attention paid, to date, to the various ways in which proteins are "tweaked" through the attachment of sugars. However, the process of glycosylation is far from a decorative function. Carbohydrates help determine the three-dimensional structures of proteins, which are inherently linked to their function and their efficacy as therapeutics. Moreover, in contrast to some of the other chemical tags employed by cells (e.g., phosphates and lipids), carbohydrates exhibit a mind-boggling diversity of structures, can confer cell-type specificity, and are crucial components of cell-to-cell signaling. At the same time, carbohydrates make problematic drug targets; they are the most difficult biological molecules to analyze and synthesize, and are rapidly broken down in the bloodstream. Despite these challenges, recent technological advances have enabled several biotechnology companies to pursue new carbohydrate-based products, sweetening the outlook for glycobiology.