Elevated levels of osteoprotegerin, a secreted tumor necrosis factor-related molecule, might be associated with adverse outcomes in patients with coronary artery disease. We measured plasma osteoprotegerin concentrations on hospital admission, at discharge, and at 1 and 6 months after discharge in a predefined subset (n=5135) of patients with acute coronary syndromes in the PLATO (Platelet Inhibition and Patient Outcomes) trial.