Background: Arterial calcification is associated with increased risk of cardiovascular events. Osteoprotegerin (OPG) is a cytokine involved in the bone metabolism and vascular calcification. Recent data support a relationship between high serum levels of OPG and increased risk for cardiovascular disease in human. The aim of this study was to evaluate the OPG serum levels in acute ischemic stroke. Our study was further designed to detect differences in serum OPG levels between subtypes of ischemic stroke.