Objective: To assess whether sildenafil citrate improves blood flow in fetal um- bilical arteries and middle cerebral arteries in pregnancies at high risk for fetal growth restriction. Methods: A quasi-experimental study was carried out at the Department of Ob- stetrics and Gynecology, Suez Canal University Hospital in Ismail- ia over the period from June 2017 to April 2018. Trans-abdominal obstetric ultrasonography (U/S) was done for 30 pregnant women aged24 to 35 years, gestational age ranged between 33- 36 weeks, at high risk for fetal growth restriction (mild pre-eclampsia, diabetes mellitus, history of previous pregnancy with a small for gestational age, stillbirth, severe pre-eclampsia or pregnancies with abnormal umbilical artery indices-above 90th centile). Fetal umbilical and middle cerebral artery blood flow Doppler indices were determined before and 2 and 6 hours after ingestion of sildenafil citrate 20 mg tablet. Results: There was a statistically significant decrease in umbilical artery Dop- pler indices before, two hours and six hours following sildenafil ci- trate therapy in the studied patients (P<0.05) and a statistically signif- icant increase in middle cerebral artery Doppler indices before, two hours and six hours following sildenafil citrate therapy in the studied patients (P<0.05). Conclusions: Sildenafil citrate significantly increases blood flow in the umbilical arteries and normalizes blood flow in fetal middle cerebral arteries in pregnancies at high risk for fetal growth restriction thereby restoring a normal fetal circulation and corrects the “brain sparing" adaptive mechanism.