Teichoic acids are a group of phosphate-containing polymers associated with the cell walls and plasma mem-branes of gram-positive bacteria; they are apparently absent from gram-nega-tive bacteria. Classically, teichoic acids were considered to be polymers of either glycerol phosphate or ribitol phosphate substituted with various glycosyl and D-alanyl ester groups (Fig. 1). This definition has more recently been broadened to include all cell wall, capsular, or membranepolymers con-taining glycerol phosphate or ribitol phosphate residues (1). The extraction, determination of structure, immunolog-ical properties, possible functions, and biosynthesis of these polymers have been the subjects of extensive investiga-tions since their discovery and have been equally extensively reviewed (1-3). Several major distinctions can be made between teichoic acids associated with cell walls and teichoic acids as-sociated with the plasma membrane. Cell wall teichoic acids are covalently linked to peptidoglycan and may ex-hibit the full range of glycerol phosphate-containing and ribitol phosphate-containing structures now included in the definition of the term teichoic acid. They do not occur in all species of gram-positive bacteria and their occurrence may also be de-pendent upon the growth conditions employed (4). Membrane teichoic acids are covalently linked to a glycolipid moiety of the plasma membrane and appear to be always of the classical glycerol phosphate polymer type (2, 5). Membrane teichoic acids are more characteristic components of gram-positive bacteria (6) than cell wall teichoic acids and their presence is not as dependent upon growth conditions