Backgrounds: Data regarding genetics of Hashimoto’s disease (HD) and Graves’ disease (GD) in Korean children are lacking. Methods: 73 patients with autoimmune thyroid disease (AITD; HD 32, GD 41) were recruited. We analyzed human leukocyte antigen (HLA) class I and HLA-DRB1 by PCR-SSP, and compared them with those of 159 controls. Results: In AITD, the allele frequencies of HLA-A*02, -B*46, -Cw*01 and -DRB1*08 were higher and those of HLA-A*30, -B*07, -Cw*07 and -DRB1*01 were lower than in controls. In HD, those of HLA-B*46 and -Cw*01 were higher and those of HLA-DRB1*01 and -Cw*07 were lower than in controls. In GD, those of HLA-A*02, -B*46, -Cw*01 and -DRB1*08 were higher and those of HLA-DRB1*07 and -Cw*07 were lower than in controls. Between HD and GD, there were no significant differences in allele frequencies. The risk of AITD in the presence of both HLA-B*46 and -Cw*01 is higher than in the presence of either allele alone. Conclusion: The susceptible and protectable alleles in HD are similar to those in GD. Coexistence of HLA-B*46 and -Cw*01 may be a genetic gene marker for early-onset AITD in Koreans.