Despite its rarity, anomalous origin of the right coronary artery (RCA) from the left coronary sinus can pose risk of sudden death. Because of this risk, many patients elect surgical correction of this anomaly. Surgical strategies for correction of this include ostioplasty, coronary artery reimplantation, and, more commonly, coronary artery bypass grafting. After coronary artery bypass grafting, some advocate ligation of the proximal RCA, speculating that competitive flow will cause graft failure. As no objective criteria for this have been established, we propose a method using of intraoperative Doppler flow measurements to guide the decision to preserve the proximal anomalous native vessel. We present three cases in which an RCA with an anomalous origin from the left sinus was corrected with coronary artery bypass grafting with the assistance of intraoperative Doppler flow measurements to guide the decision to preserve the proximal anomalous native vessel. In each case, the RCA was bypassed using a saphenous vein graft (SVG) that was used to bypass origin of the RCA. Flow through the graft was compared with and without ligation of the proximal RCA, before creation of the proximal anastomosis. In each case, flow through the SVG was not significantly reduced with the proximal RCA patent and ligation was not performed.