Coronary subclavian steal syndrome (CSSS) is a relatively uncommon entity, and its clinical spectrum is characterized by stable exertional angina and rarely as acute coronary syndrome. The diagnosis can be established easily by angiography. We report a case series of three patients with CSSS and acute coronary syndrome and we review the literature in the attempt to understand the nature of symptomatology and the mechanisms of ischemia in this condition. Our study raised some questions about the correct definition of this entity, the pathophysiology of coronary steal and the mechanisms of ischemia, in the setting of unstable angina and acute myocardial infarction.