Summary: The reliability and reliable indexes of quantitative assessment of coronary flow reserve (CFR) by using time-intensity curve (TIC) via myocardial contrast echocardiography were investigated. The TIC variables were obtained by employing acoustic densitometry (AD) technique before and after acetylcholine (Ach) injection in 12 dogs. Meanwhile, the correlation between these variables and CFR was analyzed. Among the variables derived from TIC, peak intensity (PI), area under the curve (AUC) and descending slope (DS) were increased significantly (P＜0. 05) with the increase of coronary blood flow after Ach injection. Conversely, time-to-peak (TP),half-time of descent (HT), and mean-transit-time (MTT) were decreased remarkably (P＜0. 0001). The PI and AUC ratios from post- to pre-Ach injection were strongly associated with CFR with the correlation coefficient (r) being 0. 8366 and 0. 8824, respectively. It is reliable by using the variables derived from TIC with myocardial contrast echocardiography to quantitatively evaluate regional myocardial CFR. The PI and AUC ratios from post- to pre-Ach injection are the reliable indexes for quantitative assessment of CFR.