Background: fetal growth restriction is an important cause of perinatal morbidity and mortality. The accurate assessment of fetal growth during pregnancy is difficult, but recent advances have improved this important aspect of obstetric care with positive implications for antenatal patients and their babies. Aim of the Work: to assess the effect of sildenafil citrate on color Doppler flow parameters in umbilical artery, Middle cerebral artery and Biophysical Profile in case of fetal growth restriction. Patients and Methods: this is a prospective cohort study of 100 pregnant females presenting for routine antenatal care at 28 + 0 weeks till delivery. A cohort of 100 pregnant females attending the antenatal care clinics at Al-Hussein university hospital and Bab El-Sharia university hospital during a period of 2 years from May 2016 to May 2018. Results: this study excluded the patients with undetermined gestational age, intrauterine   infection,   high   risk for aneuploidy (e.g. maternal age >40 years, detected congenital fetal anomalies in the current or previous pregnancies). All cases were followed regularly twice monthly during the seventh and eighth month and then once weekly till delivery, after the administration of 20mg of sildenafil citrate every 12 hourly starting from the 28 weeks of gestation until delivery. Conclusion: the current study conclude that, administration of Sildenafil 20 mg every 12 hourly in pregnant females  with fetal growth restriction (FGR) improved the feto-placental Doppler indices (pulsatility index and resistance index) of umbilical artery, middle cerebral artery.