Background Coronary flow reserve by thermodilution(CFRthermo) correlates well with doppler wire-derived coronary flow reserve(CFRdoppl). However, there are few data about relationship between CFRthermo and CFRdoppl in primary PCI. This study was aimed to investigate the correlation and agreement between CFRthermo and CFRdoppl in patients who undergoing primary PCI with AMI. Methods Forty-nine patients were studied. AMI patients underwent primary PCI were classified as group A(n=27, mean age 57짹12), and non-AMI patients underwent elective PCI as group B(n=22, mean age 52짹9). After PCI, CFRdoppl was measured and a pressure-temperature sensor-tipped guide wire were introduced in the target vessels. Thermodilution curves were obtained by hand injection of 3mL of room temperature saline at baseline and at adenosine-induced hyperemia. CFRthermo was compared with CFRdoppl in two groups. Results In all studied patients, a significant correlation were observed between CFRthermo and CFRdoppl(CFRthermo= 0.761CFRdoppl + 0.782, P < 0.001; r=0.72, P < 0.001). Subgroup analysis also showed correlation in both group A(CFRthermo= 1.128 CFRdoppl + 0.121, P < 0.001; r=0.73, P < 0.001) and group B(CFRthermo= 0.639 CFRdoppl + 1.068, P = 0.001; r=0.66, P = 0.001). Bland-Altman analysis revealed a closer agreement between CFRthermo and CFRdoppl(96.3% of group A, 95.5% of group B were in 2 standard deviation.) Conclusions Thermodilution is feasible method to assess coronary flow reserve in infarct-related artery, as well as noninfarct-related artery.