On basis of 35 patients who have suffered from transient global amnesia the pathophysiological mechanisms of this syndrome are discussed. Our impression is that the primary cause of this syndrome is a transient ischemia of the hippocampus, an opinion common with most earlier authors. The possibility of a unilateral hippocampal disturbance resulting in transient global amnesia is discussed. We are inclined to regard the local hippocampal ischemia as arising from insufficiency of the anterior chorioidal artery and thus as a sequel of internal carotid insufficiency, which has earlier been proved to result from various rotatory, flexion, and extension movements of the neck.