Follicle stimulating hormone (FSH) is a hormone produced by gonadotropes in the anterior pituitary gland. FSH activates ovulation in women, initiating the approximately-monthly menstrual cycle. The release of FSH causes the immature follicles to grow in the ovaries. As the follicle grows, it releases inhibin which shuts off the FSH production.

In men, FSH enhances the production of androgen binding protein by the Sertoli cells of the testes.