Neuronal cell injury after global cerebral ischemic insult is not well understood in humans. We performed serial examination of diffusion-weighted imaging and magnetic resonance spectroscopy in three patients after cardiopulmonary resuscitation. The presence of the signal for lactate in magnetic resonance spectroscopy in the acute stage after cardiopulmonary resuscitation was closely correlated to irreversible damage. In addition, high intensity in diffusion-weighted magnetic resonance image in the acute stage also predicted a poor outcome. Lesions that were positive for these factors in the acute stage led to serious brain damage in the subacute and chronic stages. The results indicated that after cardiopulmonary resuscitation, diffusion-weighted magnetic resonance imaging and magnetic resonance spectroscopy is an extremely useful modality to estimate the prognosis of patients, which is not always easy using conventional methods.