Lipid intermediates, or lipid-linked saccharides, were first discovered in bacteria where they were shown to be involved in the biosynthesis of cell wall polymers such as peptidoglycan, lipopolysaccharide, teichoic acid and capsular polysaccharides (Osborn 1969, Hemming 1974). Those studies set the stage for later experiments in eukaryotic systems which also showed the synthesis and utilization of similar types of lipid intermediates in the biosynthesis of complex carbohydrates (Waechter and Lennarz 1976). In this chapter, the lipid intermediates that have been identified in higher plants will be discussed and their role in biosynthetic reactions will be considered. The plant systems will be compared to those studies that have been done in animal and yeast systems. Figure 1 outlines a series of reactions that have been proposed to account for the formation of the lipid-linked oligosaccharide that serves as the final donor in the glycosylation of protein. These reactions are considered in detail in the ensuing pages.