Acute disseminated encephalomyelitis (ADEM) is an uncommon inflammatory disease of the central nervous system and can be defined strictly as scattered focal or multifocal (disseminated) inflammation of brain or spinal cord, or both. An ADEM usually reveals patchy demyelinated lesions with a high signal on T-2-weighted sequences. Here, we report a case of a 39-year-old mail with ADEM. Echo-planar"trace" diffusion magnetic resonance imaging revealed high signal intensity changes at the lesion sites on b=1000 s/mm(2) images, initially suggesting restricted diffusion. On corresponding apparent diffusion coefficient (ADC) maps, however, the lesions have a high signal intensity and high ADC values, compared with the normal white matter. This was consistent with the presence of elevated diffusion, and hence, vasogenic edema.