Methods r Study subjects We prospectively olled LLpcos women from women undergoing controlled ovarian stimulation (COS) in prep- aration for ME ories as previously described [6]. Diag- nosis of PCOS was made according to the Rotterdam consensus 23. All 14 PCOS women had oligo- or amen orrhea and at least 12 follicles 2-9 mm in diameter per ovary. Ten of the women had hyperandrogenemia and/or hyperandrogenism, and four had normal serum androgen levels and no clinical rogeoism. Secondary causes of androgen excess and anovulation were excluded ,Then indications for cos in the Pcos group were mala deior (7 women), ovulator defunct ailed su rovula tion induction and intra inseminations (4 women) uterine and t factor (3 women). Fourteen non-PCOS control women undergoing COS in preparation for IVF or ICSI were matched to PCOS women by age, BMI and use of GnRH agonist/antagonist prior to enrollment. Inclusion criteria for control non-PCOS women were normal ultra- 9 sonic ovarian morphology, normal ovulatoy cycles and no endocrine abnormalities. Inclusion criteria for all study women were ages between 20 adequate visualization of ovaries on transvaginal ultrasound and no hormonal treatment i.e. xclusion criteria were diminished ovarian reserve or endometriosis. The indications for cos in the control group were male factor (9 women) or tubal factor infertility (5 women). Patient clinical characteristics are given in Table 1. This study was ap- proved by Maimonides Medical Center institutional re view board. Written informed consent was obtained 4 from all participating women.