Numerous reports indicate that lipid or protein associated carbohydrates are essential for infection of cells by various viruses, bacteria, or bacterial toxins, some of which affect the nervous system. Examples of such pathogens include tetanus and botulinum neurotoxin, Shiga and Shiga-like toxins, Borrelia burgdorferi, Mycobacterium leprae, and human immunodeficiency virus. This review discusses evidence indicating that carbohydrates are essential for these pathogens to induce their deleterious effects, the putative function of the carbohydrates, and how this knowledge might be used to combat the effects of the pathogen.