In altogether 31 patients with liver cirrhosis, fatty degeneration of the liver or a morphologically normal liver the free fatty acids, glycerin, ketone bodies and triglycerides were examined as parameters of the fat metabolism after nocturnal alimentary abstinence and under 2-hour glucose infusion. Parallel to this estimations of the immune-reactive insulin and of the blood glucose were performed. In liver cirrhoses increased levels of free fatty acids, low ketone body levels, the absent correlation between ketone bodies and immune-reactive insulin under basis conditions as well as the relatively smaller reduction of the TG-values in hyperinsulinaemia were to be established. They may be explained as an expression of restricted metabolic functions of the cirrhotic liver. On the other hand from the prompt decrease of free fatty acids and glycerin under glucose-induced hyperinsulinaemia was concluded to an unrestricted efficacy of the insulin in the fatty tissue in the sense of the furthering of lipogenesis and inhibition of the lipolysis.