Right gastroepiploic artery is used as an in-situ arterial conduit in coronary revascularization, but flow competition has been reported. Between September 1998 and June 2000, 25 patients underwent coronary revascularization using right gastroepiploic artery. Coronary flow patterns were examined in 21 patients by postoperative angiography. Flow patterns were divided into 2 categories: right gastroepiploic artery-dependent (n = 16) and native coronary artery-dependent (n = 5). Flow competition was seen in 5 of the 21 patients (24%). The diameter of the right gastroepiploic artery was significantly larger in the right gastroepiploic artery-dependent group, whereas the diameter of the native coronary artery was larger in the native coronary artery-dependent group. Ten of 11 patients with 100% proximal coronary stenosis and all 3 who received a graft to the obtuse marginal branch showed a right gastroepiploic artery-dependent flow pattern. The flow pattern in the graft was determined by the size difference between the arterial conduit and the native coronary artery, the degree of proximal stenosis, and the site of the anastomosis. Further study is needed to evaluate the long-term results of coronary artery bypass grafting using right gastroepiploic artery.