The blood levels of ethanol, acetaldehyde, acetate, methanol, acetone, lactate. pyruvate, and glucose were measured in 23 male alcohol-dependent patients on days 2 to 6 after hospitalization and in 22 healthy male blood donors. Correlations between the biochemical parameters and 17 symptoms of the alcohol-withdrawal syndrome (AWS) were calculated. Abnormally high levels of ethanol, methanol, acetate, and acetone as well as hypoglycaemia were found on day 2, but lactacidaemia and pyruvataemia were pronounced throughout the observation period. AWS severity correlated positively with the acetone content on day 2 and with the acetate content on days 2 to 6. Negative correlations were found between ethanol levels and craving for alcohol, methanol levels and craving for alcohol, and between psychopathologic disorders and the total AWS severity score. The results suggest that concentrations of blood ethanol, methanol, acetate, and acetone exceeding their normal endogenous levels can be used only as indicators of recent heavy drinking. Linear discriminant analysis using the levels of the nine parameters studied enabled the correct classification of 91% to 96% of alcoholic patients during 1 week of abstinence and 100% of control subjects. The most informative parameters in the discrimination between alcoholics and controls were lactate, pyruvate, the lactate/pyruvate ratio, acetate, and acetone.