BACKGROUND: Preeclampsia is a life threatening complication of pregnancy affecting about 3-10% of pregnancies and a significant contributor to maternal and perinatal morbidity and mortality. Elevated placental production of soluble endoglin (sEng), an anti-angiogenic factor, has been implicated in the pathogenesis of preeclampsia. OBJECTIVE: The aim of the study was to compare the concentration of serum sEng during the third trimester of pregnancy in women with preeclampsia to those of normotensive pregnant women and to determine if these concentrations correlate with the severity of preeclampsia and adverse outcomes. METHODOLOGY: This was a case – control study that involved a total of 180 pregnant women – 90 with preeclampsia and 90 normotensive controls matched for gestational age, parity, and body mass index at the Lagos Island Maternity Hospital. Socio- demographic and clinical characteristics were recorded. 5ml of venous blood was collected and serum analyzed for sEng concentration using ELISA technique. Data was analyzed using SPSS 20 software. Variables were expressed in mean ± SD. Comparison of groups was done using chi- square, student t-test, and Fischer test. Correlation was with Pearson’s coefficient and p-value of <0.05 was considered statistically significant.