Myocardial injury and acute coronary syndrome have been rarely associated with amoxicillin/clavulanic acid intake. The responsible pathogenetic mechanism is described by an amplified mast cell degranulation inducing coronary artery spasm and/or acute myocardial infarction in susceptible individuals which is called Kounis syndrome. We report here a case of Kounis syndrome presented with acute coronary syndrome due to amoxicillin/clavulanic acid use. All other etiologies, including ischemic reinfarction were appropriately ruled out. (C) 2007 Elsevier Ireland Ltd. All rights reserved.