The present study was conducted to evaluate the accuracy of cerebroplacental ratios (the middle cerebral artery PI divided by the umbilical artery PI) as detected by color Doppler ultrasonography as a means of predicting intrauterine fetal distress and adverse perinatal outcome in postterm pregnancies. It included 80 pregnant ladies divided into two groups according to their gestational age, the first group (postterm group) included 40 pregnant ladies attending the out patient clinic for assessment of fetal well-being. The second group (control group) included 40 pregnant ladies with gestational age ranged from 37 to 40 weeks.