Intravenous glucose tolerance, insulin tolerance, tolbutamide, and glucagon tests were carried out in 21 patients with postnecrotic cirrhosis. Based arbitrarily on the bromsulphthalein retention they were divided into group A, nine patients with less impaired liver function, and group B, 12 patients with greater impairment of liver function. Intravenous glucose and insulin tolerances were reduced in both groups. The hypoglycaemic effect of tolbutamide was similar in the controls and in both groups of cirrhotic patients but this was achieved at higher plasma insulin levels in group B indicating resistance of the liver to the effect of endogenous insulin. The blood glucose response to glucagon was markedly impaired in group B patients which is consistent with this hypothesis. In contrast to the insulin response to glucose and tolbutamide, the insulin response to glucagon was reduced in the cirrhotic patients. Fasting human growth hormone and free fatty acid levels were elevated in both groups but they were not considered to be important factors in the production of insulin resistance.