122 women diagnosed with PCOS seeking fertility in the fertility clinic at kasr Alainy hospital will be subjected to Homeostatic model assessment for insulin resistance 1 was calculated for all participants through the equation \[glucose (mmol/L) × insulin (µU/L)\]/22.5 while homeostatic model assessment for insulin resistance 2 was calculated by the HOMA2 calculator. All women will be subjected to induction of ovulation using the Aromatase inhibitor Letrozole 2.5 mg tab twice daily from the 3rd day of the cycle for 5 days . Ultrasound follow up of follicular growth will be performed till dominant follicular size reaches 18-22 mm. FSH preparations will be introduced as needed.