Polycystic ovary syndrome (PCOS) is the most common endocrinopathy encountered in the female population of fertile age. It affects approximately 5-10% of women of reproductive age.(1) It is a syndrome with heterogeneous etiology. An important problem secondary to this syndrome is the infertility due to chronic anovulation. The diagnosis of PCOS is a diagnosis of exclusion. Two of the following three Rotterdam criteria (ESHRE/ASRM 2003) are required: hyperandrogenism (clinical and/ or biochemical), oligo- / anovulation, ultrasound morphology specific to PCOS. In the context of anovulation, folliculogenesis is disrupted, which leads to excessive accumulation of small antral and preantral follicles, which at serum level will be reflected by increased levels of Anti-Müllerian hormone (AMH). Thus, serum AMH becomes an objective and well-structured criterion, both in mono-evaluations and in correlation with classical triad classification of PCOS, resulting in increased sensitivity to 83% and 100% diagnosis specification. Serum AMH cut-off 3.15 ng /ml shows an early marker of PCOS.