Aim: Determining the effects of combined or separate estrogen and progesterone administration on lipid peroxidation, antioxidative activity (AOA), β-carotene, vitamin A and C levels in overiectomized rats.

Materials and Methods: The study was conducted on 1 control and 3 trial groups each consisted of 10 overiectomized rats. Control group received sesame oil while progesterone group received 2 mg/rat/day progesterone, estrogen group 10 mg/rat/day 17β-estradiol and estrogen + progesteron group 10 mg/rat/day 17β-estradiol+ 2 mg/rat/ day progesterone for 10 days. Blood samples of rats were collected under general anesthesia after 2 hours following last administration and checked for malondialdehyde (MDA), AOA, β-carotene, vitamin A, and C levels.

Results: Whole blood MDA levels in estrogen group were decreased as compared to control group while remained same in others. Plasma AOA levels of estrogen and estrogen + progesterone groups were higher (p<0.05) than control and progesterone groups. Plasma β-carotene levels were decreased in all trial groups when compared to control. Vitamin C levels of all groups were higher as compared to control group and were highest in estrogen + progesterone group.

Conclusion: It can be concluded that estrogen decreases lipid peroxidation and increases antioxidant capacity besides effects positively the levels of antioxidant vitamins, particularly showing that mentioned level of estrogen act as an antioxidant.