Background. To investigate the functional capacity of the right gastroepiploic artery graft (GEA) and its ability to adapt to provide adequate flow at peak myocardial demand, we investigated the feasibility of determining coronary flow reserve (CFR) provided by this vessel using transabdominal color Doppler echocardiography and the correlation between this noninvasive determination of flow reserve and nuclear stress scintigraphy. Methods. In 40 selected patients, who underwent complete arterial myocardial revascularization using the GEA and the internal thoracic arteries (ITAs), CFR of the GEA was measured at maximum coronary hyperemia induced by intravenous adenosine infusion, 7 months (range 3 to 20) after surgery. In the same period, in 31 of this group of patients, exercise thallium scintigraphy was performed. Results. We succeeded in measuring CFR in 37 of 40 patients with values ranging from 1.1 to 3.6 with an average of 2.1 ± 0.7. During adenosine infusion, mean velocity in the GEA significantly increased from 48 ± 20 to 89 ± 41 cm/sec (p ≤ 0.001), mean arterial blood pressure significantly decreased from 96 ± 11 to 87 ± 11 mm Hg (p ≤ 0.001), and heart rate significantly increased from 74 ± 11 to 87 ± 15 beats/min (p ≤ 0.001). In 8 of these 37 patients, the nuclear exercise test was positive (compatible with reversible ischemia in the distribution area of the GEA). Average CFR in these 8 patients with positive nuclear stress test was 1.46 ± 0.28 versus 2.27 ± 0.70 in those patients with a negative test (p ≤ 0.001). Conclusions. Noninvasive determination of CFR of GEAs is feasible, using transabdominal Doppler echocardiography. The present study shows that coronary vasodilator reserve and autoregulation is maintained in myocardium supplied by the GEA and that the CFR has a significant correlation with the results of noninvasive nuclear exercise testing. Therefore, noninvasive determination of CFR by transabdominal Doppler echocardiography might be a valuable contribution to functional assessment of GEAs.