Anti-Müllerian hormone (AMH) has important roles in postnatal ovarian function. Produced by ovarian granulosa cells, AMH is involved in initial follicle development. In fact, serum AMH level correlates with ovarian follicle number. In patients with polycystic ovary syndrome (PCOS), AMH levels are elevated, which indicates its potential relevance in PCOS diagnosis and management. AMH represents a useful clinical marker for the assessment of ovarian reserve in cases of subfertility caused by advanced age in women. A potential role for AMH in dominant follicle selection has also been suggested. Future challenges comprise the availability of a well-standardized assay and the development of AMH agonists and antagonists as possible tools to manipulate ovarian function for contraception or ovarian longevity.