Polycystic ovary syndrome (PCOS) affects 5-10% of women in childbearing age. Hyperinsulinemia contributes to chronic anovulation commonly encountered in women with PCOS. The first choice therapy is clomiphene citrate (CC). In CC resistant cases, the ACOG recommends the use of insulin sensitizer metformin. Other insulin sensitizing agents include rosiglitazone and pioglitazone. Pioglitazone is said to improve fertility and ovulation in patients with PCOS. CC has a long half-life (2 weeks), and this may have a negative effect on the cervical mucus and endometrium, leading to discrepancy between ovulation and conception rates. There has been a search for a compound capable of inducing ovulation but devoid of the adverse antiestrogenic effects of CC. recent studies have suggested that letrozole, an aromatase inhibitor, does not possess the adverse antiestrogenic effects of CC and is associated with higher pregnancy rates than CC treatment in patients with PCOS.