A 30-year-old man presented with a generalized seizure manifesting as decreased consciousness. Diffusion-weighted magnetic resonance imaging showed transient areas of high intensity in the gray and subcortical white matter of the left occipital and temporal lobes. The lesions did not reflect the vascular territories. After a period of over 2 weeks, his consciousness level improved associated with reduced intensity of the abnormal areas. These findings suggest that seizure induced reversible cytotoxic and vasogenic edema. Transient diffusion-weighted magnetic resonance imaging abnormalities may be associated with generalized seizures and the intensity may reflect the clinical condition.