The major histocompatibility complex (MHC) is the most important susceptibility locus for type I diabetes in humans and NOD mice. NOD mice express a single MHC class II molecule (I‐A^g7) which carries a unique β chain sequence. In humans, DQ alleles that encode DQ8 and DQ2 confer the highest risk for the disease. Soluble DQ8 and I‐A^g7 were used to directly compare the binding specificity of these MHC molecules. Peptides from three islet antigens – insulin, GAD 65 and HSP 60 – bound to both CQ8 and I‐A^g7. These peptides included epitopes that are immunodominant in NOD mice, namely insulin (9 – 23), GAD (206 – 220) and HSP 60 (441 – 460). All of these peptide sequences are highly conserved between the human and murine antigens. The binding specificity of DQ8 and I‐A^g7 was similar, but not identical, since two peptides eluted from splenocytes of NOD mice did not bind to DQ8. DQ8 formed long‐lived complexes with the majority of these peptides, indicating that DQ8 is not a poor peptide binder. These results demonstrate functional similarities between human and murine MHC class II molecules that confer susceptibility to type I diabetes.