Background: Polycystic ovarian syndrome is also called hyper-androgenic anovulation syndrome.It is a set of symptoms due to elevated male hormone in women. The major features of PCOS include menstrual dysfunction, anovulation and signs of hyperandrogens Other signs and symptoms of PCOS include hirsutism, infertility, obesity, metabolic syndrome, diabetes and obstructive sleep apnea. On examination, finding in women with PCOS may include virilizing signs, acanthosis nigricans, hypertension and enlarged ovaries (may or may not present).Ovulation induction in women with PCOS suffering from anovulatory infertility includes the use of antioestrogen, insulin sensitisers, aromatase inhibitors (Letrozole), gonadotropin (FSH) and surgical treatment. Objective: The present study aimed at comparing between the efficacy of aromatase inhibitors(letrizole), clomiphene citrate and recombinant (FSH) on induction of ovulation in polycystic ovarian syndrome. Patients and Methods: the present study was conducted on 150 patients with polycystic ovarian syndrome according to the Rotterdam criteria for polycystic ovarian syndrome with history of menstrual disturbance and whose age ranged between 18-37 years. In the current study, patients were allocated into 3 equal groups: group A (Clomiphene citrate), group B (Letrizole) and group C (Recombinant FSH). Results: Clomiphene citrate, letrizole and recombinant (FSH)were the common to be used for induction of ovulation in polycystic ovarian syndrome.In our study we proved that recombinant (FSH) is the most effective of these drugs,followed by letrizole and the least is clomiphene citrate. Conclusion: PCOS is a major cause of infertility in women.Medical treatment (induction of ovulation) is one of the major methods of management of PCOS. Recombinant (FSH) has the higest efficacy in our study.