HLA class II profile was evaluated in 64 Brazilian patients presenting with type 1 diabetes mellitus. Although the Brazilian population is highly miscegenated, HLA-DRB1*301, DRB1*04, DQB1*0302, and DQB1*0201 alleles, which are associated with the development of type 1 diabetes in several Western populations, were also overrepresented in Brazilian patients. In addition to HLA-DRB1*15 and DQB1*0602 alleles, DRB1*11, DRB1*13, and DQA1*01 allele groups were associated with protection against the development of type 1 diabetes in Brazilian patients.