This review article includes a systematic evaluation of the empirical data concerning deficits in mental ability, brain perfusion, and cerebral functioning due to chronically low blood pressure. A number of studies have provided strong evidence for reduced cognitive performance in hypotension, particularly in the domains of attention and memory. EEG studies have demonstrated that the hypotension-related poorer mental ability is also reflected in diminished cortical activity. Contrary to convention, more recent research has suggested a deficient regulation of cerebral blood flow in persons with low blood pressure. In addition to reduced tonic brain perfusion, studies demonstrated insufficient adjustment of blood flow to cognitive requirements. Altogether, these findings suggest that more attention should be allocated to chronic hypotension in both research and clinical practice.