Therefore, we suggest that: (1) PTEN plays an important role in the pathogenesis of PCOS; (2) a high level expression of PTEN in the PCOS can induce apoptosis of the preantral follicle and sinusoid follicle; (3) the final result may be the arrested development of the ovarian follicle and anovulia. This evidence concerns the gene PTEN and polycystic ovary syndrome.