Objective. To study the role of Doppler velocimetry of theِ umbilical and middle cerebral arteries, represented by the cerebroplacental ratio, and amniotic fluid volume in the prediction of adverse fetal outcome in post-term pregnancies. Design. A prospective case control study. Setting. Cairo University Teaching Hospital for Obstetrics and Gynecology. Egypt. Subjects. 60 pregnant patients divided into two groups; Group A, 30 pregnant ladies with gestational age of more than 40 weeks, Group B, 30 pregnant ladies with gestational ageranging from 37 to 40 weeks. Interventions. All patients were submitted to antenatal fetal surveillance tests including modified biophysical profile (MBPP) which consists of the non-stress test (NST), amniotic fluid index (AFI), and color Doppler velocimetry of fetoplacental and fetal vessels including MCA PI, UA PI, and CPR. Main outcome measures. The accuracy of cerebroplacental ratios (the middle cerebral artery PI divided by the umbilical artery PI) andamniotic fluid volume as a means of predicting intrauterine fetal distress and adverse perinatal outcome in post-term pregnancies. Results. Cerebroplacental ratio show highest sensitivity (95%) in comparison with other parameters, so it is a good test to reassure the obstetricians of the fetal well being. Prominent changes in AFI (i.e. <50% increase or decrease) is not associated with adverse perinatal outcome irrespective of the rate of change provided that the final value remains >5.0 cm. A significant association with FHR decelerations and presence of meconium is proved to exist when AFI is <5.0 cm. Conclusion. The addition of cerebral/umbilical ratios to antenatal surveillance protocols is expected to improve the perinatal outcome. It should be tried in the various high risk pregnancies whenever uteroplacental insufficiency is suspected