Elevated plasma concentrations and abnormal secretory patterns of GH have been found in patients with cirrhosis of the liver. Displacement of brain dopaminergic monoamines by false "neurotransmitters' produced in the gut has been postulated as a cause of encephalopathy. In this study basal GH plasma levels and their response to TRH and L-DOPA were determined in thirty-nine cirrhotic patients and fifteen controls. Eleven patients had evidence of encephalopathy (Group 1), twenty-eight did not (Group 2). Both basal levels and the mean peak response to TRH were significantly higher in the cirrhotic patients that in the controls (Group 3). Peak values were moderately, but not significantly, higher in Group 1 than in Group 2. The response to L-DOPA was considerably lower in the encephalopathic patients in comparison with the subjects of both Group 2 and Group 3. This finding is consistent with depletion of active "neurotransmitters' in CNS. Our data fail to demonstrate clearly whether the paradoxical response to TRH can also be related to these abnormalities of monoamine metabolism in cirrhotics.