Numerous reports confirmed that serum gamma-glutamyl transpeptidase (GGT) levels may be elevated in myocardial infarction and in other forms of ischemic heart disease. A similar elevation has been reported in acute coronary insufficiency. The common predisposing factor for the above-stated disorders is atherosclerosis. Considering the sensitivity of GGT to the dietary fat content, it is expected that development of atherosclerosis may influence the enzymatic activity in liver prior to the occurrence of clinical manifestations. In this study, attempts have been made to examine the liver GGT activity in rats following the administration of atherogenic diet for a period of time required for the appearance of atherosclerotic lesions. A correlation between tissue lipid fractions and the activity of enzyme was also estimated. Prolonged administration of atherogenic diet caused a fivefold rise of hepatic GGT activity when the activity was compared with the data obtained following the application of the control diet. The cholesterol and triglyceride contents were found significantly higher in animals consuming the atherogenic diet than those fed the control diet. A significant positive correlation was observed for GGT activity and cholesterol levels.