Left internal mammary artery (LIMA) is very commonly used conduit for coronary artery bypass grafting (CABG) due to its proven long term patency. The development of fistula between LIMA and pulmonary vasculature is a rare complication of this operation. Recurrent angina pectoris developed in a 73-year-old man 3 years after CABG. Coronary angiography revealed a fistulous connection between LIMA graft and the left pulmonary vasculature. Our patient was managed conservatively with acetylsalicylic acid, statin, nitrate, and angiotensin converting enzyme inhibitor. We report herein a case who developed LIMA to pulmonary vasculature fistula after the CABG.