Coronary-subclavian artery (SCA) steal syndrome is an uncommon phenomenon in which coronary flow is diverted into the SCA through the patent left internal mammary artery (LIMA) conduit due to critical subclavian stenosis. The prevalence of significant left SCA (LSCA) stenosis in patients, referred for coronary bypass surgery, has been reported to be 0.2 to 6.8%. Most patients usually present with angina pectoris, and secondary myocardial infarction is rarely reported. Herein, we present a case of coronary bypass graft in which a left anterior descending artery-LIMA graft was applied to supply the left arm due to complete LSCA occlusion. The patient was hospitalized with a diagnosis of non-ST elevation myocardial infarction.