We studied the distribution of HLA-DR and MT1, MT2, MT3 genotypes in 23 Chinese children with insulin-dependent diabetes mellitus (IDDM). The frequency of DR3 was 48% in IDDM children compared to 14% of normal controls (corrected p = 0.0098, RR = 5.70). The frequency of DR4 was not increased. These differences when compared with the results of Western populations may contribute to the relative rarity of IDDM among Chinese children.