High-resolution 1H NMR images of the isolated perfused rabbit heart were recorded before and after the induction of regional ischemia while the heart was arrested. On T2-weighted images the ischemic region appeared darker than the surrounding tissue and a 28% reduction in T2 was measured from the images. Infusion of an NMR contrast agent demonstrated that the hypointense region on the T2-weighted image was from the ischemic region, which was further confirmed by histological analysis of the heart. It is proposed that the decreased T2 in the ischemic region may be a consequence of changes in water compartmentalization. It is possible that these changes may be used to follow the evolution of tissue injury during ischemia, and therefore provide information regarding the transition between reversible to irreversible injury in the isolated perfused heart.