Objective: To detect serum levels of soluble endoglin (sEng) during different periods in normal pregnancy and patients with preeclampsia and evaluate its role in the pathogenesis of preeclampsia. Methods: Women were enrolled in following groups:healthy pregnant control(n = 43) and preeclampsia patients,which contained mild preeclampsia(n = 31),severe preeclampsia (n = 26). The serum sEng levels were measured by enzyme linked immunoassay (ELISA). Results: The concentration of sEng in control group during 12~16,20~24,28~32 and 37~41 weeks were (7.7 ± 1.5),(8.2 ± 1.6),(9.3 ± 1.7) and (11.4 ± 2.6) ng/ml,respectively. They were(7.8 ± 1.5),(9.4 ± 1.8),(14.2 ± 2.9),(21.1 ± 3.7) ng/ml in mild preeclampsia group,and(7.9 ± 1.6),(12.5 ± 2.8),(25.2 ± 3.9),(33.6 ± 4.5) ng/ml in severe preeclampsia group,respectively. The levels of maternal plasma sEng were significantly higher in the preeclamptic women than in normal controls during the latter three periods(P < 0.01) except for the first period. Conclusion: Alterations in the levels of sEng in maternal serum were associated with the occurrence and development of preeclampsia.