Background: To investigate the relationship between HLA-DR, DQ antigen, and intracranial aneurysm in the Han nationality. Methods: We compared the occurrence of HLA-DR and HLA-DQ antigens in patients with intracranial saccular aneurysm and in the control group by PCR and agarose gel electrophoresis. Results: No statistically significant correlation between HLA-DR, HLA-DQ antigen frequency, and the pathogenesis and clinical characteristics of intracranial aneurysm has been found. Conclusions: We have not found any relationship between HLA-DR and HLA-DQ antigen frequency, haplotype frequency, and pathogenesis and clinical characteristics of intracranial aneurysm, but the patients who presented with HLA-DR53, DR52, DQ7(3), and DQ5(1) seem to be more likely to bear multiple intracranial aneurysms. (c) 2006 Elsevier Inc. All rights reserved.