AIM OF WORK: the aim of our study was to compare the value of first trimester three-dimensional placental power Doppler flow indices versus second trimester uterine artery Doppler in predicting preeclampsia and IUGR Patients and methods: Our study included 500 pregnant women. They were subjected to measurement of placental vascular indices at their first trimester (11- 13 weeks) and blood flow indices assessment of the uterine artery at second trimester (20-22weeks). Results: Placental vascular indices were measured in first trimester, the placental vascular indices including VI, FI and VFI were found to have a sensitivity of 89.4%, 60.3% and 49.2% respectively and specificity of 48.6%, 39.3% and 47.3% respectively. While uterine artery pulsatility index when done in the second trimester was found to have a sensitivity of 100% and specificity 61% for prediction of preeclampsia. Conclusion: We concluded that placental vascular indices in the first trimester were more sensitive, but slightly less specific than uterine artery pulsatility index when done in second trimester in prediction of preeclampsia.