Possible effects of a high-cholesterol diet on the oxidant/antioxidant status in various tissues from rats and the effects of the combination of vitamins C and E on these parameters and on hypercholesterolemia were investigated. Twenty-four Sprague-Dawley type rats were randomly divided into three groups. The control group (group 1) was fed on a rat pellet diet. The study groups (groups 2 and 3) were fed on a high-cholesterol diet for 3 months. Rats in group 3 were supplemented with vitamins C (100 mg/kg intraperitoneally ) and E (60 mg/kg intramuscularly ) three times a week throughout the study. At the end of the study period, all animals were sacrificed and their heart, kidney, liver and testis surgically removed to measure oxidant and antioxidant parameters. Blood samples were also obtained from the animals. We observed that serum total cholesterol levels significantly increased in the study groups after the study period. The increase in the blood cholesterol level in group 3 was, however, significantly lower than that in group 2. As to the oxidant-antioxidant parameters, there were different results among the tissues. In conclusion, our results suggest that high serum cholesterol level does not lead to oxidation reactions in the early phase of hypercholesterolemia, and antioxidant vitamins supplementation increases antioxidant potential values of the tissues and decreases the blood total cholesterol level in the cholesterol-supplemented animals.