This article summarizes the neuroradiology of Alzheimer's disease (AD) and details the radiologic features that permit the identification of patients with normal pressure hydrocephalus (NPH). Patients with presumed AD show a characteristic atrophy pattern with specific involvement of the temporal lobes and hippocampus. These findings have prognostic implications. Patients with NPH typically show severe motoric and gait deficits and initially mild cognitive impairment. Marked improvement is shown in select patients after ventricular shunting.