Abstract: Nonradioactive sequence-specific oligonucleotide probes for the polymorphic HLA class II genes have been used to type samples from 51 Caucasian patients with the autoimmune liver disease, primary biliary cirrhosis, and 240 Caucasian controls. Although the allelic distribution at the DPB1 locus showed no significant variation between patients and controls, there was heterogeneity in the distribution of DR-DQ haplotypes where the frequency of the DRB1*0801-DQA1*0401/0601-DQB1*04 haplotype was significantly increased in the patients, suggesting it confers susceptibility to this disease. Two other haplotypes, DRB1*1501-DQA1*0102-DQB1*0602 and DRB1*1302-DQA1*0102-DQB1*0604, were significantly reduced in the patients, suggesting they confer protection. Tests of the individual loci show that resistance to this disease is most strongly associated with the DQA1*0102 allele shared by both protective haplotypes. Due to linkage disequilibrium it is unclear whether multiple genes or a single locus on the susceptible DR8 haplotype are needed for predisposition. These data show that distinct HLA class II alleles confer both predisposition and resistance to PBC and provide insight into the role that these genes may play in the immunopathogenesis of this disease.