Oxidative stress plays an important role in the pathogenesis of myocardial repair and remodeling after myocardial infarction (MI). Nitroxide free radicals have been used as redox-sensitive MRI contrasts agents in preclinical studies to assess tumor redox status. We tested the hypothesis that dynamic nitroxide-enhanced MRI can detect oxidative stress in MI. Imaging was performed in healthy control mice and in mice one day post-MI. The ratio of the MRI signal decay between the infarcted anterolateral wall and the noninfarcted septum was significantly higher in mice after MI, indicating that nitroxide-enhanced MRI can detect increased oxidative stress in infarcted myocardium.