Background : Noninvasive assessment of coronary endothelial-dependent vasomotion is important for the evaluation of patients with coronary artery disease(CAD). The aim of this investigation was to test whether the infusion of low-dose adenosine contributes to endothelial-dependent vasodilation in humans. Methods: In 67 subjects (mean age 52짹11 yrs, M:F=39 :28) with chest pain and normal coronary angiogram, the changes of peak diastolic velocity were measured before and during cold pressure test(CPT-CFR), the infusion of low dose adenosine (Low-CFR, 15 關g/min/kg)(Figure,left) and the infusion of high dose adenosine(High-CFR, 140 關g/min/kg) with transthoracic Doppler echocardiography(TTE) in distal left anterior descending coronary artery. Results: 1.Low-CFR was closely related to CPT-CFR (r= 0.55, p<0.0005)(Figure, right). 2. Low-CFR was weakly related to High-CFR(r= 0.276, p=0.038). 3. Low-CFR was 1.16짹0.09 in subjects with more than 2 risk factors of CAD and 1.43짹0.17 in subjects with less than 1 risk factor.(p<0.005) Conclusion: Measurement of flow reserve capacity using low-dose adenosine and TTE is a promising noninvasive method to assess coronary endothelial-dependent vasomotion.