Objective: We aimed to determine the fetal cerebro-placental Doppler indices and modified myocardial performance index (Mod-myocardial performance index (MPI)) in this homogenous group of postdated pregnancies. Methods: A total of 92 singleton pregnant women were included in this prospective study. The study involved three groups; full term control (Group 1, n = 42, 39 0/7 to 40 6/7 week' gestation), late term (Group 2, n = 34, 41 0/7 to 41 6/7 week' gestation) and post term (Group 3, n = 16, >= 42 0/7 weeks' gestation). Each participant underwent a Doppler assessment of the fetal umbilical artery (UA), middle cerebral artery (MCA), Mod-MPI. We determined the correlation of the Doppler indices and mod-MPI in patients with unfavorable outcome. Results: MCA pulcatility indices (PI), cerebroplacental ratio (CPR) values were significantly higher in the control group than those in the late-term and post-term groups (Group 1: 1.63 +/- 0.3, Group 2: 1.27 +/- 0.51, Group 3: 1.13 +/- 0.22, respectively, p < .001). The Mod-MPI was significantly higher in the late-term and post-term groups than in the control group (Group 1:0.38 +/- 0.1, Group 2: 0.59 +/- 0.09, Group 3: 0.60 +/- 0.08, respectively, p < .001. MCA PI and CPR were only significantly lower in patients with unfavorable outcome). The threshold value for CPR levels for predicting unfavorable outcome in postdate pregnancies was calculated as 1.11 (area under curve [AUC] 0.762, confidence interval [CI] 0.575-0.95) with 72.7% sensitivity and 71.8% specificity. Conclusions: Fetal Mod-MPI does not differ in postdate pregnancies with favorable and unfavorable outcome. The monitorization of fetal well-being with CPR may help to clinicians to select patient for expectant management in postdate pregnancies.