Objective:To analysis the features of apoptosis in placental trophoblasts of patients with severe preeclampsia,and study the relationship between the trophoblastic apoptosis and the etiology and pathophysiology of preeclampsia. Methods:To obtain the evidences of apoptosis in the placental trophoblasts of patients with severe preeclampsia,the techniques of the electron microscope scanning,TUNEL and FCM were applied. Results:①In the ultrastructure of severe preeclamptic placental trophoblasts under the electron microscope scanning,there also were typic morphologic changes of apoptosis including anomalo-nucleus,pyknosis,abnormal distribution of heterochromatin,deeply-stained mitochondrial matrix in cytoplasm,clouding or disarrangement of mitochondrial crest,vacuoles in placental trophoblast cells,and so on. ②Under the detection of TUNEL technique,it was found that there were more numbers of apoptotic trophoblasts in the placenta of severe preeclampsia with fewer apoptotic cells appearing in the placenta of NC. ③In normal placental tissues,no markedly apoptotic peak(Apo peak) was found in the diagrams of FCM. However,there all were the markedly apoptotic peaks in the FCM diagrams of the severe preeclamptic placental tissues. Conclusion:Trophoblstic apoptosis in the placenta may contribute to the etiology or pathophysiology of preeclampsia.