Abstract: Polycystic ovary syndrome （（PCOS） is a common endocrine disorder in fertile women ， Hyperandrogenism is currently thought to be central to the pathogenesis of PCOS. Androgen biological actions depend not only on serum androgen levels but also are modulated by androgen receptor （AR） activity. The gene encoding AR located on the X-chromosome （Xq11-12） contains a highly polymorphic CAG microsatellite polymorphism in exon1，which is impacted by X-chromosome inactivation pattern .In vitro studies showed that the shorter CAG repeats have a higher transcription activity. Recently， many studies have proved that the AR-CAG polymorphism is associated with PCOS， which may provides an effective evidence for the pathogenesis and therapy.

Key words: Polycystic ovary syndrome, Androgen receptor, CAG polymorphism, X-chromosome inactivation