The posterior cerebral arteries (PCAs) are the major sources of blood supply to the midbrain, thalamus, occipital lobes, inferior and medial temporal lobes, and portions of the posterior inferior parietal lobes. The PCAs originate from the terminal bifurcation of the basilar artery, encircle the midbrain, and then divide into cortical branches as they reach the dorsal surface of the midbrain. Patients with PCA stenosis may have transient ischemic attacks (TIAs) alone, or they may precede infarction. The main clinical feature distinguishing proximal PCA occlusion from the other types of PCA strokes is hemiplegia. Unilateral and bilateral PCA territory infarctions can also result from mass lesions that cause transtentorial herniation and increased intracranial pressure. The temporal and calcarine artery branches are most often involved. Patients with bilateral infarctions involving the lingual and fusiform gyri in the inferior portions of the temporal lobes often manifest a restless, hyperactive state.