It has been reported that cerebral blood flow is decreased in chronic alcoholics without neurological diseases. We performed SPECT by the resting and vascular reserve (RVR) method in 11 chronic alcoholics (mean age 59.1+/-10.4, all males) and 11 age-matched healthy controls (mean age 58.8+/-10.1, all males). The resting and vascular reserve (RVR) method is a consecutive Tc-99m-ECD SPECT study before and after acetazolamide administration with adjunctive radionuclide angiography, which is easy to perform for a routine clinical study and quite useful for evaluating regional cerebral blood flow and the cerebrovascular response to acetazolamide. Regional cerebral blood flows in almost all regions in the alcoholic group were lower than those in the control group. However, there were no significant differences in increased rates of blood flow in response to acetazolamide in almost all regions between the chronic alcoholic group and the control group. In both groups, the increased rates of blood flow in response to acetazolamide in the supratentorial region, cerebellum, and brain stem were 30-40%, 20-25%, and 42-48%, respectively. The cerebrovascular response to acetazolamide in chronic alcoholics was not impaired, therefore the reduction of brain metabolism may be one of the important factors causing the decreased cerebral blood flow in chronic alcoholics.