Bilateral anterior paramedian thalamic infarction resulting from occlusion of a bilaterally distributed thalamosubthalamic paramedian artery was demonstrated on CT in two patients. Patient 1 presented with a transient coma followed by asterixis, hypersomnia, vertical gaze disturbances, profound Korsakoff amnesic syndrome, and a subcortical dementia. Patient 2, with a predominantly right-sided thalamic infarct, showed good recovery from amnesia and vertical gaze disturbances. However, patient 1 remained with severe amnesia and mild subcortical dementia at follow-up 1 year later. These and similar reported cases constitute a lacunar syndrome with characteristic clinical and CT features.