The aim of this study was to investigate the effect of chlorfenvinphos administered at a single dose of 0.02 LD₅₀ on the activity of serum of liver damage indicatory enzymes, such as
ß-glucoronidase (BGR), acid phosphatase (AcP) and alanine and aspartate aminotransferases (ALT and AST), as well as on the ac-tivities of superoxide dismutase (SOD) and catalase (CAT) in erythrocytes and liver. The animals were divided into two groups: the control group, which received oil, and the experimental groups, which received oil solution of chlorfenvinphos at a dose of 0.02 LD₅₀. After 1, 24 and 48 hours of intoxication with chlorfenvinphos the blood samples were collected and livers were quickly removed. This study indicates that acute intoxication with chlorfenvinphos administered at a dose of 0.02 LD₅₀ leads to liver function disturbances, which is a likely result of increased generation of reactive oxygen species.