Aim To observe the early dynamic changes of the serum level of myeloperoxidase （MPO） after percutaneous coronary intervention （PCI） in patients with acute myocardial infarction （AMI）, and investigate the prognostic value of MPO for in-hospital major adverse cardiovascular events （MACE） in AMI patients treated by PCI. MethodsA total of 68 consecutive patients hospitalized with chest pain for the first time who had the onset of symptoms within 12 h were selected and arteriography was performed. They were divided into 44 patients treated by PCI （stent group） and 22 patients assessed by coronary angiography only （angiography group）. And 15 patients with normal coronary arteries were selected as normal control group. Blood samples were collected at baseline （T0） and 30 min, 4 h, 12 h and 24 h （T1, T2, T3, T4） after surgery, MPO and high-sensitive C-reactive protein （hs-CRP） were measured using an enzyme-linked immunosorbent assay （ELISA）. Patient in-hospital MACE of stent group was recorded. Results （1）Both MPO and hs-CRP levels were significantly higher in stent or angiography group than in normal control group, but there were no significant difference between the stent and angiography group. （2）The MPO and hs-CRP levels of stent group reached to the peak at T2, T4, respectively, and were significantly higher than T0 （P<0.01）. Both MPO and hs-CRP of the two groups all showed a trend of gradually increasing, and reached to their highest value. The peak value of the two factors in stent group were higher than that in angiograph group significantly （P<0.01）. No dynamic changes in levels of MPO and hs-CRP were found in normal control group before and after arteriography at the different time points. （3）There was a total of 9 patients with MACE during the hospitalization in stent group. The receiver operating characteristic curve （ROC curve） analysis revealed the level of MPO at T2 had the highest predictive value for MACE ［area under curve （AUC）＝0.823, cut-off point＝792.850 μg/L, sensitivity＝88.9%, specificity＝70.3%, P＝0.003］. Conclusions MPO is a sensitive resemble of the early inflammatory response in patients with AMI after PCI. It significantly elevated and rapidly reached to the peak in the early stage after PCI. And the predictive value of MPO after PCI was superior at preoperative for in-hospital MACE due to the patients with AMI treated by PCI.