We report our experience with a case of a left atrial mass coexisting with a coronary artery-left atrial fistula. The abnormal vessels extended from the right coronary artery and left circumflex artery to the tumor in the left atrium and were aggregated within the tumor. An efflux of the contrast media was also noted from the tumor into the left atrium. Tumor resection and ligation of the abnormal vessels were performed as surgical interventions. The outcomes were favorable. The tumor was pathologically diagnosed as a myxoma, but its association with the abnormal vessels was unknown.