Objective: to compare adding clomiphene citrate to letrozole in comparison with letrozole only Patients and method : A total of 64 infertile woman with PCOS were assessed in this randomized controlled trial in Department of Obstetrics and Gynecology at Imbaba General hospital and Banha university hospital . Results: The serum pregnancy test was positive in only (6,3%) group A who receive letrazole alone while shows (12.5%) in group B who took combined therapy with no significance in P value(0.39) so group B shows higher pregnancy rates, The six weeks pulsations shows higher percentages in group B (9.4%) in compare to Group A (3.1%) with P value of (0.3) , There is good significance in the number of follicles (with P value 0.006) with appearance of one follicle in group B was higher than group A (68.8% in group B versus 37.5% in group A) ,Also the appearance of 2 mature follicles happen only in group B (6.3%). the follicular size appeared significance with P value (