To clarify the effects of normal aging on the cerebral blood flow, regional cerebral blood flow measurements++ using a Patlak Plot method of 99mTc-ECD were performed in 53 normal volunteers aged 18 to 87 years old (mean = 47.9 years). The subjects, 29 men and 24 women, were normal on clinical examination, and had neither a history of neurological nor psychiatric disease and no abnormal CT or MRI images. Statistical parametric mapping (SPM) was used for automatching and an objective approach to analysis of SPECT image data. Global cerebral blood flow showed a significant decline with age (r = 0.406). The SPM analysis (voxel height; p < 0.001, Bonferroni correction; p < 0.05) demonstrated significant age-related decrease of relative rCBF in prefrontal cortices, anterior cingulate giri, and insular cortices-temporal poles bilaterally, these affected areas belonged to limbic or association cortices. Therefore, these decreases in rCBF may suggest cognitive changes that occur during normal aging.