The course of galactosamine hepatitis induced by 1.0 g/kg i.p. injected galactosamine (Ga1N) was investigated a sequential study in normal rats, in colectomized rats, and in rats being endotoxin resistent against both exogenous and endogenous endotoxin. Clinical symptoms of Ga1N-hepatitis such as pyrogen reaction, disseminated intravascular coagulation, arterial hypotension, and hypoglycaemia correlated significantly with the development of endotoxaemia, which was detected by means of the limulus gelation test (L.G.T.) Ga1N refractoriness was found after colectomy, a situation, in which gram negative bacterias and their endotoxins were eliminated. Ga1N refractoriness was also observed in case of endotoxin resistence. It is concluded that endotoxins contribute significantly to the pathogenesis of "Ga1N-hepatitis" and its clinical symptoms.