In order to evaluate the correlation between the cognitive-behavioral performances and the regional blood-perfusion deficits of the brain, 18 elderly subjects affected by dementia of probably primary degenerative character have been studied. The patients were first examined by psychometric tests and then submitted to brain Single Photon Emission Computed Tomography (SPECT) using [(99m)Technetium]-d,l-hexamethyl-propylene-amine-oxine (Tc-HMPAO) for regional blood flow evaluation (rCBF). The cognitive-behavioral functions have been estimated by Mini Mental State Examination (MMSE), Randt Memory Test, Rey's 15 Words, Corsi's Block Tapping Test, Word Fluency Test, Sentence Construction, Sketch Copy, Toulouse-Pieron's test. Digit Symbol Test from Wechsler Adult Intelligence Scale, and the Progressive Matrices 1947 (PM 47). The cerebral blood flow reduction in left occipital lobe and left frontal lobe explained 67% of the visuo-verbal memory impairment of the patients. These results suggest that the decrease of cognitive functions is related to some extent to a lower cerebral blood perfusion.