The distribution of HLA-A, -B, and -DR antigens in 53 Southern Chinese patients with Hashimoto's thyroiditis including 33 with goitre and 20 without goitre was compared with the distribution in 100 Southern Chinese controls. There was a significantly increased prevalence of HLA Bw46 in the nongoiterous patients and of HLA DRw9 in both groups of patients, but only for HLA DRw9 in the goiterous group was the increase significant after adjustment for the number of antigens studied. Based on these findings and those in other autoimmune diseases it is considered that the haplotype Bw46, DRw9 in Chinese takes the place of B8, DR3 in Caucasians in carrying genes which predispose to the development of auto-immune disease.