In this study the investigators shall compare the effect of combined letrozole-metformin with that of combined letrozole-metformin-pioglitazone in ovulation induction in CC-resistant PCOS women.This will be a prospective comparative clinical trial in which 2 groups of women will be generated (groups A and B) using the sealed envelopes randomization method.Group A (50 women) will receive: letrozole 2.5 mg/day from 3rd day of the cycle for 5 days and (pioglitazone 15 mg + metformin 850 mg) once daily from 1st day of the cycle for 10 days. Group B (50 women) will receive letrozole 2.5 mg/day from 3rd day of the cycle for 5 days and metformin 500 mg three times daily from continuously untill pregncy occurrs. Ovulation will be monitored by vaginal ultrasound and serum estrogen and progesterone.