Objective: The aim of this study is to evaluate antioxidant parameters as well as levels of lipid peroxidation, paraoxonase enzyme, and nitrotyrosine in the follicular fluid and embryo culture media among patients under IVF treatment. Material and methods: Fifty-one patients who underwent IVF / ICSI were enrolled in this prospective study at the IVF Center of University Hospital. A long agonist protocol was used in 22 cases for controlled ovarian stimulation, and an antagonist protocol was used in 29 cases. Two-hundred sixty follicular fluid samples from a total of 454 follicular fluids obtained from the cases and cell culture media of 51 transferred embryos (one from each case) were examined. Follicle fluids and embryo cell culture media were divided into groups according to oocyte fertilization, the protocol applied, the day of transfer, the quality of the embryos obtained and whether pregnancy was achieved. medium obtained from 51 individually cultured embryos and investigating their relationship with the controlled ovarian stimulation applied Results: Thiobarbiturate reactive substances (TBARS) levels were significantly lower in the fertilized oocytes follicular fluids compared to the unfertilized ones (21 vs. 29.75 nmol/ml, p = 0.002). There were no differences with regard to other parameters. Trolox Equivalent Antioxidant Capacity (TEAC) levels were higher both in the fertilized and unfertilized oocytes in the agonist protocol group compared to the antagonist protocol group. As to the quality of embryos, there were no differences between the groups in terms of the investigated parameters and between the pregnant and the nonpregnant groups in follicular fluid analysis. TEAC levels were higher in the embryo cell culture media in the pregnant group during the day 2 embryo transfer. we found no association between follicular fluid TEAC levels and fertilization rates in total, however, TBARS values were significantly higher in the unfertilized group, suggesting that