We present a patient with nonketotic hyperosmolar coma who exhibited extra-pontine myelinolysis as demonstrated by the findings including magnetic resonance imaging (MRI). The lesions appeared as widespread symmetrical hyperintensities that involved the subcortical white matter of the frontal, temporal, and parietal lobes. Thinning of the cerebral cortices was observed. The center of the pons was only slightly affected. The patient ultimately died of pneumonia. The abrupt changes in serum sodium concentration and/or osmolarity, induced not only by treatment of hyponatremia, but by alteration to the hypernatremic state, may have contributed to the development of pontine and extra-pontine myelinolysis. To our knowledge, this is the first case in which the MRI results corresponded to previously reported autopsy findings of extra-pontine form by Okeda et al. in pontine and extra-pontine myelinolysis.