The frequencies of HLA-DR and DQ antigens in 24 Chinese patients with Behçet's disease (BD) were calculated and compared with those in 130 healthy control Chinese and those in 80 Chinese patients with recurrent oral ulcers (ROU). Although an increased trend of DRw6 and DRw8 antigens in patients with BD was noted, there was no significant difference in frequencies of HLA-DR and DQ antigens between patients with BD and healthy control subjects or patients with ROU after correction of P values (Pc > 0.05). Further analysis of our data of the phenotype frequencies of DRw6 and DRw8 antigens according to the subtypes of BD also showed the increased frequencies of DRw6 and DRw8 antigens in patients with mucocutaneous type of BD as compared with those in healthy control subjects. However, only the phenotype frequency of DRw8 antigen in patients with mucocutaneous type of BD was significantly higher than that in patients with ROU (P < 0.005, Pc < 0.05, relative risk = 17.7, and etiologic fraction = 0.30). This significant increase of the phenotype frequency suggests that the gene coding for HLA-DRw8 antigen in patients with ROU was only partially (30%) responsible for susceptibility to the mucocutaneous type of BD.