In the present study, we attempted to replicate the finding of an increased frequency of HLA-A2 in men with early-onset (less than or equal to 60 years) Alzheimer disease (AD). HLA data obtained on 167 patients (including 19 men with early-onset AD) from three geographic regions (North Carolina, Great Britain, and Finland) failed to replicate the result. A recent prospective study from Oregon, however, confirmed the association. Studies demonstrating the association suggest its presence in sporadic rather than familial AD. These results indicate a variable HLA/AD association, with some factor such as geographic region or disease familiality contributing to this variability.