Seventy-four North American Caucasian insulin dependent diabetics are presented and compared to 100 healthy controls relative to HLA-A and B locus antigens. A highly significant increase in the frequency of HLA-B8 was found (p < 0.01, relative risk 3.67). The presence of HLA-A11 conferred statistically significant protection against disease development in these patients (p < 0.01, relative risk 0.19). There was no significant difference in the frequency of HLA-B7, B8, or B15 between the study and control groups. The patient group does show a significant increase in heterozygosity for HLA-B8 and HLA-B15 when compared to healthy controls (p < 0.05, relative risk 7.17). Increased incidence of HLA-B18 has previously been noted in French and English populations only. Since most of our HLA-B18 patients are of English extraction, it is concluded tht the altered incidence of the HLA-B18 allele in insulin dependent diabetes does persist in this migratory European population.