Objective To explore the changes of placental growth factor (PLGF) in patients with acute coronary syndrome (ACS).Methods One hundred and twelve patients were divided into four groups according to clinical data and coronary angiography:non-coronary artery disease (non-CAD) group (27 cases),stable angina (SA) group (28 cases ),unstable angina (UA) group (29 cases) and acute myocardial infarction (AMI) group (28 cases).Fifty-seven patients with ACS were divided into single lesion group (19 cases),twice lesion group ( 16 cases) and triple lesion group (22 cases) by coronary angiography,and 0-7 scores group (23 cases),8-15 scores group (27 cases) and 16-32 scores group (7 cases) by Jenkins scores.The serum PLGF levels of all the cases were determined on admission.The serum PLGF levels of 40 cases receiving percutaneous coronary intervention (PCI) were determined at 30 min before operation,the first and second day after operation.Results The serum PLGF levels of AMI group and UA group were (38.33 ±10.14) ng/L and (37.44 ± 13.32) ng/L respectively,which were significant higher than that of SA group [(20.90 ± 3.88) ng/L] and non-CAD group [(20.34 ±4.53) ng/L](P＜ 0.01),and there was no significant difference between AMI group and UA group,SA group and non-CAD group (P ＞0.05).There was no significant difference in the serum PLGF level among triple lesion group,twice lesion group and single lesion group (P ＞ 0.05 ).There was no significant difference in the serum PLGF level among 0-7 scores group,8-15scores group and 16-32 scores group (P ＞ 0.05).The serum PLGF level of patients receiving PCI on the first day after operation [ (32.03 ± 7.41 ) ng/L] was significantly higher than that before operation [ (23.86 ± 6.91 ) ng/L](P＜ 0.05 ),and on the second day after operation the serum PLGF level [ (29.37 ± 6.99) ng/L] was less than that on the first day after operation,showing a fall tendency(P＞ 0.05).Pearson correlation analysis showed that the serum PLGF levels in patients with ACS were not related with cardiac troponin T and creatine kinase isozyme-MB (r =-0.158,P=0.421;r =0.302,P=0.118).Conclusion The serum PLGF level of ACS patients is an inflammatory marker reflecting coronary atherosclerotic plaque destabilizing or plaque ruptured,and may also play an important role in early diagnosis of the borderline case of ACS.