With CC use, although ovulation rate reaches up to 80%, PR is much lower probably due to adverse effects of CC on the endometrium. In this study, 120 patients were classified to 4 groups to detect the adverse effects of the drug against a control group and also to confirm and compare the ability of EE and vaginal sildenafil to revert these changes. The deleterious effects of CC were clear as well as the power of both drugs to revert these changes, but, unfortunately; pregnancy rate was, still, very low which indicates the need for a larger study with a wider scale and multicentre participation.