Background: Preeclampsia is a pregnancy-specific multisystem disease that is characterized by development of hypertension and proteinuria after 20 weeks of gestation, resolving by 6-12 weeks postpartum in previous normotensive women. The pursuit of safe, reliable, and cost-effective screening tests for prediction of preeclampsia has been the goal of researchers for many decades, with the aim of improving maternal and fetal outcome, despite the fact that the only current effective treatment remains delivery of fetus and placenta. Objective: The aim of this study is to compare mean platelet volume (MPV) in pre-eclamptic and normal pregnant women in the third trimester of pregnancy, and to evaluate whether this parameter have a prognostic significance in determining the presence of preeclampsia. Patients and methods: This study was done at Kafr Elsheikh General Hospital from January 2018 to December 2018. 80 pregnant women in their third trimester (from 31weeks gestation to completed 37 weeks gestation) were selected to participate in the study. Result: We found in our study that CBC, and MPV values do not have any determining effect on the presence of preeclampsia but the platelet count showed difference. In the literature, papers that include conflicting results especially on MPV values are available, yet this fact is most probably due to the differences between the methods and/or equipment used. Conclusion: Our study found that MPV values do not have any determining effect on the presence of preeclampsia.