To determine the prevalence of central nervous system damage due to ethanol, we evaluated 40 asymptomatic chronic alcoholics and 20 age-matched controls. Studies included neuropsychological testing, brain 99mTc-HMPAO SPECT, and morphometric analysis by CT scan. In the qualitative analysis, 30 of the 40 alcoholics showed hypoperfused areas on SPECT scan. In the semiquantitative analysis, alcoholics exhibited significant reduction in regional cerebral blood flow (rCBF) ratio of all brain lobes compared to controls (p < 0.001). The rCBF ratio was mainly reduced in frontal lobes (65%). Only 11 alcoholics showed significant frontal lobe atrophy in the morphometric analysis; most also had abnormalities on SPECT scan. Alcoholics exhibited significant impairment of frontal tasks and visuospatial skills. Frontal test impairment was independently related to both frontal atrophy and hypoperfusion. In a group of ten alcoholics in whom another SPECT scan was performed after 2 mo of ethanol abstinence, rCBF ratio of the frontal lobes normalized in eight, without frontal atrophy. In patients without frontal atrophy, reduced rCBF ratio of the anterior portion of the frontal lobes correlated negatively with frontal test results (r = -0.6535, p < 0.001). A significant negative correlation between cerebral perfusion and the amount of ethanol consumed in the month prior to study was observed (r = -0.6289, p < 0.001). In conclusion, asymptomatic chronic alcoholics frequently showed reversible frontal lobe hypoperfusion, which is related to recent ethanol intake, reflects brain function impairment and is independent of brain atrophy.