Objectives:The polycystic ovary syndrome (PCOS) is conventionally defined as a combination of hyperandrogenism and anovulation with polycystic ovaries. Insulin-like growth factor I (IGF-I) is a 70 aa polypeptide hormone with endocrine, paracrine, and autocrine effects. it is now established that the ovary is a site of IGF-I gene expression and reception. However, this huge amount of data could be somehow distractive since different species may produce distinct IGFs (or their relative binding proteins and receptors) at different stages of follicular development. Objective: The aim of this work was to determine the serum level of IGF-I to evaluate its role in PCOS. Subjects and Methods: Twenty-five infertile women with PCOS diagnosed by ultrasound examination and a history of oligomenorrhea, hirsutism and obesity were studied. Serum levels of insulin-like growth factor-1 (IGF-1) and hormonal profile were measured. Fifteen healthy and fertile women with regular menstrual cycles served as a comparison group. Results: The serum levels of IGF-I were significantly elevated in women with PCOS compared with control and there was positive correlation between IGF-I from one side and each of BMI, W/H ratio, LH, LH/FSH ratio, TSN, T/SHBG ratio, right and left ovarian volumes. On the other side, IGF-I was inversely correlated with SHBG, right and left uterine artery PI and RI. Conclusion: The significant finding of this study is that PCOS patients have increased circulating IGF-I levels than healthy controls and it can be used as a biochemical marker for PCOS.