Melatonin is a potent antioxidant, has been proposed to improve ovarian response and oocyte quality in assisted reproductive technologies (ART). This study evaluated the effects of melatonin supplementation on follicular fluid melatonin levels, hormonal profiles, and reproductive outcomes in women undergoing in vitro fertilization (IVF). Follicular fluid and serum melatonin levels, oocyte quality, embryo development, and pregnancy rates were assessed.