Derangements in glucose, amino acid and protein metabolism in patients with liver cirrhosis were examined with special reference to plasma levels of human growth hormone (HGH). Changes in blood glucose, IRI (immunoreactive insulin), HGH, FFA (free fatty acid) and plasma free amino acid levels were determined in controls and patients following either oral glucose load, protein feeding or intravenous arginine infusion. 1) In patients with liver cirrhosis, incidence of glucose intolerance after glucose tolerance test (GTT) was high and IRI levels were elevated in the fasting state as well as after glucose, protein or arginine loads. 2) Fasting levels of blood HGH were significantly higher in liver cirrhosis than in controls. GTT revealed that blood HGH levels decreased slightly during the rising phase of blood glucose, and conversely, increased during the falling phase of glucose (180 minutes after the glucose load) both in controls and in patients. In cirrhotic patients, marked increases in HGH levels were observed both 120 minutes after the protein load and 60 minutes after the arginine infusion. 3) Fasting levels of serum FFA were significantly higher in liver cirrhosis than in controls. Both controls and patients, however, showed a similar pattern of change in FFA levels following GTT or protein ingestion, i.e. a minimum value 120 minutes after the load and a gradual increase thereafter. 4) Fasting levels of plasma free amino acids were significantly higher in cirrhotic patients than in controls. After the glucose load, however, slight decrease was noted in some amino acid levels. All the amino acid levels examined were elevated following protein ingestion, particularly in cirrhotic patients. 5) A positive correlation was demonstrated in cirrhotic patients between total plasma free amino acids and maximal HGH responses following protein ingestion. Similar significant correlations were observed between the maximal HGH response and the plasma level of several amino acids such as His., Ser., Gly., Thr., Ala., and Ileu., respectively. 6) In cirrhotic patients, negative correlations were demonstrated between fasting levels of serum albumin and total plasma free amino acids or maximal HGH responses, respectively, after the protein ingestion. From these results it was inferred that derangements in the metabolism of protein and amino acids in cirrhotic patients may result in an increase in plasma free amino acid level which in turn stimulates HGH secretion. It was surmised that the HGH levels so elevated in the patients may cause FFA mobilization which in effect results in the glucose intolerance.