Follicle-stimulating hormone (FSH) is essential for reproductive function in both men and women. In females, it stimulates ovarian follicles, promoting estrogen production and egg maturation, while in males, it supports sperm production by acting on Sertoli cells in the testes. FSH secretion is regulated by the hypothalamic-pituitary-gonadal (HPG) axis, ensuring hormonal balance for fertility.Fluctuations in FSH levels can indicate reproductive health issues. In women, high FSH levels may signal diminished ovarian reserve or menopause, whereas low levels can indicate hypothalamic or pituitary dysfunction. In men, elevated FSH suggests testicular failure, while low levels may point to hypogonadotropic hypogonadism. Conditions like Turner syndrome, Klinefelter syndrome, PCOS, and endocrine disorders can further affect FSH function in both sexes.FSH-based treatments play a key role in fertility therapies, such as stimulating ovulation in women undergoing in vitro fertilization (IVF) and enhancing sperm production in men with low sperm count. Lifestyle factors, including stress, diet, and exposure to endocrine disruptors, also impact FSH levels, influencing reproductive health. Understanding FSH’s role in both sexes is vital for diagnosing and managing fertility and hormonal disorders, ensuring optimal reproductive function.