PCOS is the most common endocrine disorder among women between the ages of 18 and 44. It affects approximately 2% to 20% of this age group depending on how it is defined. PCOS is due to a combination of genetic and environmental factors. Objective: To compare the efficacy of Clomiphene citrate and Tamoxifen in induction of ovulation in women with polycystic ovary syndrome. Patients and Methods: This clinical trial study was conducted at Al-Husien Hospital from June 2019 to December 2019 after approval of the research ethics committee, on 100 patients with P.C.O. The participants were recruited from women attending the outpatient infertility clinic of Al-Husien Hospital.Patients are classified randomly into 2 groups: Group A: 50 patients (clomiphene Group). Group B: 50 patients (tamoxifene Group).Results: Ovulation rate was significantly better under tamoxifen therapy. Pregnancy rate was significantly better under tamoxifen therapy. Number of stimulated follicles was not significantly different between the two drugs.Endometrial thickness was significantly better under tamoxifen therapy "both preovulatory and midluteal". Endometrial perfusion volume (EV), Vascularization index (VI), and Vascularization flow index (VFI) were significantly better under tamoxifen therapy. Adverse effects with thetwo drugs were non-significant. Endometrialperfusion indices weresignificantly better in pregnant versus non-pregnantcases.Conclusion:Tamoxifen can give similar or even better results than clomiphene citrate in induction of ovulation in women with PCOS. Each of them can be used as a first line option for induction of ovulation in women with PCOS "in selected cases".