Abstract Background: Female causes account for 30 percent of the overall infertility cases, five percent were attributed to uterine factors. Endometrial thickness (ET) is one of the best predictors of implantation rate and continued success rate for pregnancy. There were possible beneficial effects of sildenafil citrate or estradiol on endometrial receptivity so some reports discussed these potential effects. Aim of Study: Was to compare the effect of vaginal Silde-nafil citrate and Estradiol valerate on endometrial receptivity in clomiphene-induced cycle infertile females. Patients and Methods: This Randomized control study was conducted on 44 infertile women undergoing induction by Clomiphen Citrate attending infertility and ultrasound (U/S) unit, Obstetrics & Gynecology Department, Zagazig University Hospital, during the period from December 2018 to August 2019. Patients were randomized into 2 groups (22 in each group); group 1 received Sildenafil (Respatio 20mg/8hr film coated tablets vaginally for 5 days starting from day 8th) and group 2 received oral estradiol valerate (Cyclo-Progynova 2mg, white tablets, BAYER Schering pharma), one tablet every 12 houre from day 8th till triggering of ovulation). Results: The results of present study showed that there was no statistically significant difference between the studied groups regarding age, Type of infertility, body mass index (BMI), follicle stimulating hormone (FSH), luteinizing hor-mone (LH), Thyroid stimulating hormone (TSH), prolactin, ovulation rate, follicles number and size, results of pregnancy test and fetal pulse detection between studied group. But there was a statistically significant difference between them in endometrial thickness on the day of triggering. Conclusion: It could be concluded from this study that vaginal use of sildenafil citrate 20mg or oral Ethinyl Estradiol in females undergoing induction of ovulation lead to increase endometrial thickness and support embryo growth. Both have the same effect on pregnancy rate but Ethinyl Estradiol has better results on endometrial thickness than sildenafil.