It has been shown that after more than two decades of work on the structure and mode of action of the vancomycin group of antibiotics we have quite a detailed picture of aspects of their binding in vitro. Our introduction has indicated that these antibiotics are of continuing practical importance, whether in clinical use or animal husbandry. It is clear, however, that if one desires to modify these compounds to produce more effective antibiotic agents, more work is required--particularly to understand better the role of the sugar moieties. Nevertheless, with our present knowledge of the structure and mode of action of the antibiotics we can be fairly confident that they represent a group of compounds specifically evolved to aid the survival of the producing organisms by killing or inactivating competing gram-positive bacteria.