A 71-year-old man presented with sudden onset of vertigo and a 77-year-old man suffered consciousness disturbance. Diffusion-weighted magnetic resonance (MR) imaging on admission showed hyperintense areas in the left cerebellar hemisphere in the first patient and in the brainstem in the second patient. Both patients were treated with argatroban and edaravone, and the neurological deficits markedly improved one month after admission. T2-weighted MR imaging one month after the onset showed much smaller hyperintense areas compared with the findings on admission in both patients. These results indicate that findings of hyperintense areas by diffusion-weighted MR imaging in the acute stage of ischemic cerebrovascular disease indicate not only the ischemic core but also parts of the reversible incomplete ischemic lesion and suggest that intensive treatment in the acute stage might reverse ischemic brain damage in some patients.