First-pass MRI using gadolinium-based contrast agents is widely used to image myocardial perfusion. However, gadolinium is contraindicated for patients with severely impaired renal function (a substantial portion of heart disease patients), and methods that do not employ gadolinium are needed. Nitroxide stable free radicals are non-metallic compounds with an unpaired electron and, correspondingly, are paramagnetic and T1-shortening. We investigated first-pass nitroxide-enhanced perfusion MRI of the heart as an alternative to first-pass gadolinium-enhanced MRI. Five C57Bl/6 mice underwent first-pass imaging with the nitroxide agent 3CP and the results showed that nitroxide-enhanced MRI can quantify regional myocardial blood flow, as the average myocardial perfusion was 7.0±1.3 ml/g/min, a value in the normal range for mice.