Microbial heat stable endotoxins comprise part of most animal feedstuffs. These components have become the subject of considerable interest in later years because of the demonstration of acute toxicity, intravascular coagulation and generalized Shwartzman’s reaction in connection with intravenous injections of endotoxins (Nordstoga 1976). Endotoxins are normally present in the intestine of man and animals, but seem only to be absorbed under special conditions. Of particular interest is the “sudden infant death syndrome” which has been described for infants receiving cow milk (Di Luzio & Friedmann 1973). Absorption of endotoxins may also occur in adults e.g. in connection with γ-irradiation, immunosuppression, transplantations, severe traumatic lesions and burns (Nordstoga). It is supposed that endotoxins play an important role in the development of shock under these conditions (Nordstoga). Fine (1972) reported that exogenously administered endotoxins may break down the defence mechanisms and lead to continuous absorption of endotoxins from the intestine.