BACKGROUND: Acute (AIAU) and chronic (AICU) acetylsalicylic acid (ASA)-intolerant urticaria are the major phenotypes of ASA hypersensitivity. OBJECTIVE: We compared clinical features, immunologic findings and a HLA marker between AIAU and AICU. Method: We enrolled 232 patients with AIAU, 244 patients with AICU and 232 non-atopic normal controls (NC). Serum total and specific IgE to house dust mites (HDM) and Staphylococcal superantigens were measured by immunoCAP(R) system. Serum myeloperoxidase, IL-8, IL-18 and TGF-beta1 were measured by ELISA. We measured antinuclear antibody by the indirect immunofluorescence method, and antithyroglobulin, antimicrosomal antibodies, and IgG to cytokeratin 14 by ELISA. HLA-DRB1*1302-DQB1*0609 was analyzed by a high resolution technique. RESULT: The atopy rate, and the levels of serum total and specific IgE to HDMs and TSST-1, and serum IL-18 and TGF-beta1 were significantly higher in both AIAU and AICU groups than NC. There were no significant differences in the prevalence of autoantibodies between the AIAU and AICU patients. The prevalence of HLA-DRB1*1302-DQB1* 0609 was higher in both the AIAU and AICU patients. CONCLUSION: Atopy is a common predisposing factor for both AIAU and AICU phenotypes. Associations with autoantibodies were suggested in the pathogenesis of AIAU as well as AICU. HLA-DRB1*1302-DQB1*0609 can be a genetic marker for both AIAU and AICU.