Melatonin is a neurotransmitter released from the pineal gland. The presence of receptor sites in the hypothalamus, pituitary gland, ovaries, and testicles and secretion of pituitary hormones (FSH and LH) are some of the effects of this hormone on reproduction. In addition to its systemic effect, it also showed an effect on ovarian physiology with the detection of high levels in the follicular fluid and the presence of melatonin receptors in the ovarian cells. In addition, it has been determined that melatonin affects follicular growth, oocyte maturation, ovulation, and luteal function. It has been stated that the effects of melatonin on the male reproductive system are indirectly effective through the gonads and indirectly by affecting the hormones. Again, some studies have expressed that melatonin has strong antioxidant properties and affects reproductive physiology due to this effect. This section discusses the effect of melatonin on male and female reproductive physiology.