Background: Preeclampsia (PE) is still a major obstetrical problem world-wide. First trimester prediction of PE is of great clinical importance, as it would allow clinicians to focus on high-risk groups and initiate prophylactic medical treatment. The first stage of pre-eclampsia begins in the first trimester by impaired placentation. High-resistant spiral arteries can be detected from the 11 th week of gestation by uterine artery (UtA) Doppler examination. Objective: To assess the relationship between 1st trimester uterine artery pulsatility index (UtA PI) and the development of early onset PE. Patients and Methods: Prospective observational study was performed at Mansoura University Hospital. This study was conducted on 109 pregnant women who attended their routine antenatal care visits at the Outpatient Obstetrics and Gynecology Clinic of Mansoura University Hospital. Results: There were statistically high significant difference between both groups in the BMI (p = 0.003), and no statistically significant difference as regards the age, gravidity and gestational age (p > 0.05). Statistically significant difference was evident between two groups in the mean values of UtA PI (p = 0.028). The best cutoff value of UtA PI for the prediction of early onset preeclampsia was ≥ 2.03 with accuracy of 0.79, and that of BMI was ≥ 35 with accuracy of 0.93. Conclusion:This study revealed that first trimester uterine artery Doppler can be used as a reliable screening test for prediction of preeclampsia in high risk women. It is a reliable, noninvasive method of examining uteroplacental perfusion. Abnormal UA Doppler ultrasonography (elevated PI) in 11-14 weeks' gestation can predict pre-eclampsia.