The aim of this study is evaluation of vaginal progesterone effect on pregnancy rate in infertile women with polycystic ovary syndrome. The single-center clinical trial study will be performed on 200 infertile patients with inclusion criteria that referred to Kashan infertility center in 2012. Inclusion criteria consist 20 -35 years, having Rotterdam criteria (having 2 from 3 following criteria: Oligomenorrehea or amenorrhea, polycystic ovaries in sonography, clinical or biochemical evidences of hyperandrogenism). The patient with abnormal hormonal assay in the third day of menstruation (including FSH, TSH, prolactin, 17 Hydroxy progesterone and testosterone), tubal obstruction in HSG or laparoscopy and infertility due to male factor will be excluded. Patients will receive letrozole (5 mg) or clomiphene (100 mg) daily during 3-7 days of menstruation. Then, gonadotropin(150 IU) daily will be taken from 5-9 days of cycle. Control sonography for evaluation of ovarian response and endometrial thickness will be done on 10th or 11th day of cycle and gonadotropin dose will be adjusted. If there are at least one dominant follicle with 18-20 mm and endometrial thickness is 6-8 mm in sonography, HCG ampoule (5000 IU) intramuscular will be injected. Then, patients randomly assigned to case and control groups. Case group, will be received vaginal progesterone suppository (400 mg) daily for 14 days and control group will not receive progesterone. On last day of receiving progesterone in case group, pregnancy test will be done in two groups.