The effect of alcohol intoxication on regional cerebral blood flow (rCBF) is unclear. The few published studies provide a mixed picture of alcohol effects, suggesting that blood flow increases at low doses and decreases at higher doses of alcohol. Using the cerebral blood flow agent 99mtechnetium hexamethyl-propylene-amine-oxime (HMPAO) and image reconstruction with single photon emission computed tomography (SPECT), we evaluated the effect of an oral dose of ethanol (0.6 g/kg) on rCBF in two age-stratified groups of healthy, nonalcoholic men (12 age 22-37 and 12 age 63-77). Intoxication was associated with a significant 4% increase in global cortical CBF (t = 2.54, p = 0.02). Changes in HMPAO uptake were negatively correlated to ethanol levels in the entire group (r = -0.47, p = 0.04). This relationship was seen in the older subgroup (r = -0.70, p = 0.05), but not in the younger group (r = -0.34, p = 0.26). In contrast, the younger group showed a significant positive correlation between rCBF and increases in acetate levels (r = 0.71, p < 0.01), which was not seen in the older group (r = -0.02, p = 0.96). These findings suggest that both acetate and alcohol contribute to the changes in CBF seen in the intoxication syndrome and that their relative influence is age-dependent.