Abstract: Objective To study the relation between plasma brain natriuretic peptide(BNP) and serum creatine kinase MB(CK-MB) level in patients with acute myocardial infarction(AMI) following primary percutaneous coronary intervention(PCI).Methods Sixty-three consecutive patients with AMI were divided into two groups according to the timing of PCI,namely direct PCI and indirect PCI groups.Plasma BNP levels were measured in all patients on admission and at 4,24 and 48 h after admission.The CK-MB level was measured every 3 h on the first day of hospitalization,every 6 h on the second day and every 12 h on the third day.Results BNP level increased gradually following admission and began to decrease 48 h after admission in the two groups of patients.The peak BNP level occurred at 24 h after admission,and the BNP levels in patients of indirect PCI group were significantly higher than that of direct PCI group at 4,24 and 48 h after admission.The peak CK-MB level of the direct PCI group occurred significantly earlier than that of the indirect group.Conclusion Plasma BNP level may serve as an important objective indicator for recanalization of the infarct-related arteries following PCI in the early stage of AMI,which can help in the decision on clinical treatment plans for AMI.