Preeclampsia (PE) is a medical condition characterized by hypertension and proteinuria in pregnant females following 20 weeks of gestation. It is the most common cause of fetal morbidity and mortality, which has no curative therapeutic strategy, except for delivery of the placenta. The association between PE and aberrant microRNA (miRNA) expression in placentas was first reported in 2007 and a number of other similar findings have since been demonstrated.The aim of this study was to assess the level of expression of miR-155 in Egyptian women with preeclampsia and its role in pathogenesis and prognosis of the disease. This study was a case control study included a total of 40 pregnant females; 9 cases with early onset PEdiagnosed < 34 weeks of gestation whose mean age was 32.4 years, and 21 case of late onset PEdiagnosed ≥ 34 weeks of gestation whose mean age was 32.2 years admitted to the obstetrics and gynaecology department, Banha University Hospitals, in addition to 10 normotensive pregnant women of matched age as a control group. MIRNA 155 expression level were in PE cases when compared to control groups (p < 0.001). MIRNA 155 expression level showed no significant difference between early onset and late onset PE. miRNA 155 expression showed significantly higher level in PE than normotensive pregnant females with no difference between early and late onset PE.