Background: The purpose of the current study was to evaluate the possible effect of follicular fluid paraoxonase 3 (PON 3) on oocyte quality and sex hormones. Methods: This descriptive-analytical study was performed on totally 90 enrolled women including fifty infertile women presenting with polycystic ovaries and unilateral tubal factor and forty fertile women with male factor infertility referring to Umm-al-Banin Infertility Clinic in Dezful, Iran for in vitro fertilization during October 2018 to November 2019. Oocyte removal was carried out under transvaginal ultrasound guidance, and follicular fluid (FF) was removed and preserved to detect PON3, estrogen, and progesterone levels. In addition, oocyte number and quality were assessed and its association with PON3 activity in the FF was evaluated. One-way ANOVA and Fisher's least significant difference (LSD) were used for data analysis and p≤0.05 were considered statistically significant. Results: A significant increase was observed in the total number of the oocytes and mature metaphase II oocytes with ≥20 pg/ml of PON3 concentration in the FF (p≤0.05). Moreover, a positive relationship was shown between the increased estradiol level in follicular fluid and PON3, so that the highest estradiol level was observed in the amount of 31-40 pg/ml of PON3 (p≤0.05). Conclusion: According to the results, as the number of the mature oocytes increased, the amount of PON3 as well as estradiol levels in the FF increased. This research displays an increase in the level of PON3 with mature oocytes, thus supporting the indirect evidence for the function of PON3 in follicle development.