Eighteen patients with postnecrotic cirrhosis of liver, including three patients who had had a portosystemic shunt operation, and 19 normal controls were studied. The tests performed included monocyte insulin receptor assay, iv glucose tolerance test, glucagon test, and insulin tolerance test. Insulin resistance was documented by the presence of fasting hyperglycemia and glucose intolerance together with hyperinsulinemia as well as resistance to exogenous insulin. The binding of [125I]insulin to monocyte insulin receptors was significantly decreased in cirrhotic patients compared with that in controls (P less than 0.02), and this was due to a significant decrease in the high affinity association constant (P less than 0.005). There was a significant negative correlation between the fasting insulin level and maximum [125I]insulin binding in cirrhotic patients (r = -0.8; P less than 0.02). Cirrhotics that had had a shunt operation showed a higher fasting insulin level, a greater insulin resistance, and a smaller maximum [125I]insulin binding to insulin receptors than those without shunt. All of these findings suggested a down-regulatory effect of hyperinsulinemia on the monocyte insulin receptors. An impaired glycemic response to glucagon was also found in cirrhotics, the exact mechanism of which remains to be elucidated. However, as the increases in plasma cAMP after glucagon were similar in cirrhotics and controls, the fault apparently did not lie in the glucagon receptor.