Using PET with [(15)O]H2O, we examined age in relation to regional cerebral blood flow (rCBF) among young to mid-life adults. Previous work has largely contrasted rCBF between young and elderly age groups dichotomously. This study maps the continuum of normal age-related changes in rCBF from early to mid-adulthood. We obtained images from 37 healthy volunteers between 19 and 50 years of age during an eyes-closed resting baseline condition. There was a negative correlation between age and rCBF in mesial frontal cortex, involving the anterior cingulate region (r = 0.63, p<0.001). These findings reflect differences in the distribution of rCBF evident in early to mid-adulthood that may be associated with subsequent changes in memory and executive functioning in later life.