aimed at ,evaluating endometrial and sub endometrial vascular changes before and after endometrial injury, and evaluating the value of endometrial injury in improving pregnancy rates among patients with unexplained infertility .Methods :One hundred and twenty women with unexplained infertility were included in the study .Divided randomly into two groups Group I: (60 patients): (control group) Group II (60 patients):( study group) All the patients received (CC) and HMG,On day 5 of the cycle, Doppler examination was performed to all patients. Also on day 5, but only for group (II} patients, local endometrial injury was performed. Doppler studies was repeated, for all our patients, on the same day of prescribing HCG .Results :there was no statistically significant differences between the two groups in uterine PI and RI in in day of HCG, administration..the sub endometrial blood flow was statistically higher in the study group compared to control group(55% vs 20% ) (p value 0.001**) on the day of HCG. clinical pregnancy rate was significantly higher in the study group than in the control group (18.3 % and 6.7 % ,respectively,( P = 0.053) .Conclusion :Local endometrial injury increase pregnancy rate in un explained infertility ,Doppler study has an important role in evaluating sub endometrial blood flow before and after local endometrial injury .Based on our conclusions we may recommend local endometrial injury in un explained infertility .Key word :unexplained infertility, , endometrial injury, pregnancy