PolyCystic Ovary Syndrome (PCOS) is the first endocrinopathy of women of child-bearing age and the leading cause of anovulatory infertility. The pathophysiology of this syndrome is complex and involves genetic traits highlighted by GWAS and epigenetic traits with DNA methylation modifications. Initially described as an ovarian disease, works carried out over recent years were turned towards neuroendocrine disorder involving GABAergic pathways, KNDy neurons and a possible role of prenatal androgen exposure determined by animal models. Clinically, PCOS leads to many complications including psychological and emotional disorders demonstrated in large populations of PCOS women. © 2019 Published by Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Les Must de l'Endocrinologie 2019 réalisé avec le soutien institutionnel de Ipsen-Pharma.