Abstract: Objective To analyze the correlation between pressure-derived collateral coronary flow (PDCF) and Rentrop grade of patients with acute myocardial infarction (AMI). Methods PDCF, determined by the ratio of Pw/Pa, was measured in 29 patients with AMI of the first onset who received primary percutaneous coronary intervention (PCI) within 12 h after the onset. Sufficient collateral flow (group A, n=19) was defined as PDCF>0.24 and insufficient collateral flow (group B, n=10) as PDCF≤0.24. Rentrop grade of the collateral flow was evaluated by coronary angiography. Echocardiography was performed on the 3rd and 30th day after PCI. The left ventricular ejection fraction, end-systolic and end-diastolic volumes, and the related indexes were obtained. Result Rentrop grade was significantly related to PDCF (r=0.75, P<0.01), but a wide range of PDCF was observed in patients with Rentrop grade≤1. Conclusion PDCF measurement allows quantitative evaluation of the collateral flow in patients with AMI.