In 34 cows aged 4 to 10 years, the authors denoted the peptidase activity in the blood sera, the general level of the albumin and its fractions and performed the bromosulphthalic test. The group of healthy cows and groups with changes in the liver caused by the liver-fluke parasite have been separated. In cows with recent changes of the liver the peptidase activity is most intensive. The remaining samples give results typical for the hepatic inflammatory incidences. In cows with chronic changes the peptidase activity is similar to that characteristic for healthy cows.