Glutathione (GSH) and cysteine were determined in the plasma and the erythrocytes of alcoholic and non-alcoholic cirrhotics as fluorescent monobromobimane derivatives by high-performance liquid chromatography (HPLC). Cirrhotic patients displayed a significant decrease of plasma GSH, as well as of plasma cysteine, that was related to the degree of liver disease but not to the nutritional conditions. On the contrary, erythrocyte cysteine was found to increase significantly in all cirrhotics, particularly in alcoholics, regardless of the severity of disease. In an attempt to find a possible explanation of these alterations, the GSH synthesizing enzymes, gamma-glutamylcysteine synthetase (GC-s) and GSH synthetase (GSH-s) activities were determined in the erythrocytes. GSH-s activity was significantly lower in cirrhotic patients, whereas GC-s activity did not differ in the three groups.