Abstract： Objective To investigate the expression and clinical significance of platelet-derived growth factor A (PDGF-A) on placenta tissue from pre-eclampsia.Methods The expression of PDGF-A in the placenta of 38 pre-eclampsia patients and 22 normal pregnant women at third trimester was detected by immunohistochemistry method.Results (1)PDGF-A was mainly expressed in the cytomembrane and cytoplasm of cytotrophoblasts and the endothelial cell of capillary in placenta.(2) The rates of PDGF-A expression of cytotrophoblasts were 63% (24/38) in pre-eclampsia group and 32% (7/22) in normal pregnancy group,which exhibited significant difference (P ＜0.05).(3) The rates of PDGF-A expression of endothelial cell were 68% (26/38) in pre-eclampsia group and 27% (6/22) in normal pregnancy group,which also showed significant difference (P ＜0.01).(4)The rates of PDGF-A expression of cytotrophoblasts were 39% (7/18) in mild pre-eclampsia patients and 85% (17/20) in severe pre-eclampsia,which reached statistical difference (P ＜ 0.01).Conclusion The increasing expression of PDGF-A in cytotrophoblast and endothelial cell in placenta might confer the occurrence and progression of preeclampsia.