Twenty-one unrelated Caucasian patients with Primary Biliary Cirrhosis were typed for HLA—A, B, C and HLA-DRw antigens. The antigens HLA-A1, HLA-B8 and HLA-DRw3 were found in increased frequency in relation to the control group. When the P values were corrected for the number of antigens tested only the increase of HLA—DRw4 remained significantly different from the control group (P corr. < 0.004). The antigen HLA—DRw3 was carried by 12 out of 21 patients (57.1%) in comparison to 11 out of 74 (14.8%) normal unrelated Caucasian subjects.