Activin is a member of the transforming growth factor-beta superfamily and is a polypeptide growth factor. Activin regulates follicle growth, gonadotropin responsiveness, steroidogenesis, oocyte maturation, ovulation, and corpus luteum function in the ovary via a local autocrine/paracrine effect. Activin measurement A level in serum and follicular fluid during the preovulatory stage in PCOS women undergoing an IVF/ICSI cycle to predict fertilization capacity earlier Fifty infertile couples, 25 with PCOS and 25 without PCOS, who attended Al Nahrain University in Baghdad, Iraq's High Institute of Infertility Diagnosis and Assisted Reproductive Technologies. The females that participated were between the ages of 18 and 40. On the day of oocyte retrieval, the level of Activin A in serum and follicular fluid was measured. Activin A levels in PCOS women's serum (activin A=1274 77.9) and follicular fluid (activin A =1038 50.3) compared to non-PCOS women's serum (activin A=453 25.74) and follicular fluid (Activin A=450 23.73). The study shows no correlation between activin A hormone with oocytes characteristics and fertilization rate in PCOS women with a significant increase of activin A hormone in the serum and FF of PCOS women compared to non PCOS women. Activin A level can predict a diagnosis of PCOS in addition to positive predictive pregnancy but not indicator of fertilization capacity in PCOS women.