Abstract: Objective　To investigate the clinical significance of serum cystatin C（Cys C）in the diagnosis of severe preeclampsia. Methods　The serum samples were collected from 797 normal pregnant women in the different stages of gestation following perinatal healthy examination（normal pregnant group），95 pregnant women with severe preeclampsia and 216 healthy non-pregnant women（healthy non-pregnant group）.The serum Cys C and creatinine（Cr）were measured，and the clinical significance of serum Cys C and Cr in the diagnosis of severe preeclampsia was analyzed by receiver operating characteristic（ROC）curve. Results　The serum levels of Cys C elevated from middle-trimester（P＜0.05），and increased significantly after 28 weeks′ gestation compared to healthy non-pregnant group（P＜0.01）.Compared to normal pregnant group in the same gestational period，all serum levels of Cys C increased in early onset and late onset of severe preeclampsia（P＜0.01）.For the early onset of severe preeclampsia，serum level of Cys C was significantly higher than that for the late onset of severe preeclampsia. However，the levels of Cr increased slightly in the early and late onsets of severe preeclampsia（P＞0.05）. ROC analysis on the levels of Cys C showed that an area under the ROC curve（AUC）was 0.96. Conclusions　The serum level of Cys C reflects really the renal damage of pregnant women for severe preeclampsia，and it has a high diagnosis significance.

Key words: Cystatin C, Severe preeclampsia, Renal damage