Effect of chronic ethanol administration on some enzyme activities was studied in plasma membranes, brain homogenate cytoplasmic reticulum and cytosol, liver homogenate and microsomal fractions and blood serum. Ethanol was ingested as a constituent of isocaloric "semiliquid" diet. The investigation was carried out to estimate the diagnostic value of certain enzymes in evaluation of alcohol intoxication. In male rats ethanol caused remarkable hyperlipidemia, accumulation of lipids in liver tissue and elevation of gamma-glutamyl transpeptidase activity in blood serum and brain tissue. In liver tissue moderate induction of glucose-6-phosphatase, NADPH-cytochrome c reductase and alkaline phosphatase was observed. The putative mechanism of elevation of organospecific enzyme activities in blood serum during chronic ethanol consumption is discussed.