The term endotoxin is used to designate the relatively homogenous group of toxic substances which exist as polysaccharideprotein-lipid complexes in Gram-negative micro-organisms.38 Lysates of Gram-positive hemolytic streptococci also possess endotoxic properties.36 Considerable confusion has existed as a result of the variety of names given to these substances by different investigators. They have been known as toxic antigens, polysaccharide toxins, Boivin antigens, or Shwartzman-active toxins. Two important features of these substances are their ubiquity as contaminants and their biologic potency. The active agent in fever or nonspecific-protein therapy is endotoxin.8 Their biological effects include profound vasomotor disturbances, alterations in the white cell and platelet counts, metabolic alterations, tumor necrosis, and the Shwartzman reaction. With repeated doses there is a rapid appearance of a state of nonspecific resistance or tolerance against further endotoxin effects. A review of the ophthalmic literature has yielded many examples of ocular effects of endotoxin