Background: Sildenafil citrate is a phosphor-diestrase enzyme 5 inhibitor that leads to increasing the cyclic guanosine monophosphate and so enhancing the vasodilator effect of nitric oxide through which it may increase placental perfusion. So, it is used to treat pre-eclampsia. Objective: To evaluate the efficacy of low dose sildenafil in the treatment of intra uterine growth restriction by estimating fetal biometry and fetal Doppler parameters using trans-abdominal ultrasound. Patients and methods: This was a case control study carried on 40 pregnant female, at outpatient clinic of Department of Obstetrics and Gynecology at Zagazig General Hospital with intrauterine growth restriction singleton pregnancy. IUGR was diagnosed with ultrasound and fetal Doppler and gestational age ranged from 26 week of gestation to 31 week of gestation according to first day of last menstrual period in regular cycle patients or first trimestric visit ultrasound. Results: Umbilical artery Pulsitility Index (PI) in study and control groups before and after therapy showing statistically significant decrease in PI in study group compared to control group after therapy. Improvement in cerebroplacental ratio in study group compared to control group after therapy. There was no statistically significant difference between both groups regarding gestational age at delivery. There was a statistically significant difference regarding changes in Amniotic Fluid Index (AFI) in both groups after therapy. Conclusion: The administration of oral sildenafil tablets (20 mg twice a day) for 6 weeks improved Doppler indices in umbilical artery and cerebroplacental ratio, yet it had no effect on gestational age at neither birth nor birth weight.