Anti-Müllerian hormone (AMH), also known as Müllerian inhibitory substance, is a useful marker of ovarian function. Granulosa cells of growing follicles secrete AMH, and its serum levels reflect the remaining follicular pool and thus the remaining length of a woman's reproductive lifespan. Serum AMH measurement can be used as a marker of ovarian dysfunction such as primary ovarian insufficiency, polycystic ovarian syndrome and granulosa cell tumors. Furthermore, it helps to estimate ovarian damage due to chemotherapy or surgery and can be used as a tool in infertility treatment. The use of AMH in clinical practice will likely become more common in the future as the new automatic assay methods become available.