Internal mammary artery (IMA) grafts have been shown to be superior to saphenous vein grafts in terms of rare atherosclerotic involvement, biochemical and physical qualities, and long-term patency rates. The IMA originates from the subclavian artery, just distal to the vertebral artery, and an occlusion or a hemodynamically significant stenosis proximal to the IMA ostium would cause a pressure drop distally and a reversal of flow from the coronary arteries to the IMA in patients with this graft. This condition is referred to as “coronary subclavian steal syndrome” (CSSS). In most cases, the cause of this syndrome is atherosclerotic disease; however, other causes of subclavian artery stenosis (SAS) have the potential to lead to CSSS. Patients with CSSS present with the symptoms of myocardial ischemia due to coronary steal, vertebrobasilar insufficiency, or limb ischemia. Discrepancy in the blood pressure (BP) measurements in two arms should warn the clinician of SAS. A diminished pulse or the bruit of jet flow on the lesion side can be noticed. Doppler ultrasonography, computed tomography angiography, and magnetic resonance angiography are safe and accurate noninvasive modes of diagnosis. Treatment can be surgical or percutaneous.