Abstractβ2−Microglobulin display was examined in 131 liver biopsies from patients with acute and chronic type B hepatitis, using an indirect immunoperoxidase method. Enhanced expression of β2−microglobulin on hepatocyte membranes was observed in patients with acute hepatitis, chronic active hepatitis with moderate to severe activity and cirrhosis, when compared with normal liver. In acute hepatitis, β2−microglobulin‐positive hepatocytes were mainly observed in perivenular areas in association with bridging necrosis. In chronic hepatitis, β2−microglobulin‐positive hepatocytes were observed mainly in periportal zones and in some areas of lobular activty.Diffuse‐enhanced display of β2−microglobulin on hepatocytes was observed in 5 of 6 patients treated with lymphoblastoid interferon as part of a trial of antiviral therapy. The mechanism by which β2−microglobulin display is enhanced on hepatocytes in patients not treated with interferon is uncertain. However, display of β2−microglobulin on hepatocytes probably reflects display of HLA‐A, B and C antigens and may influence the course of hepatitis B virus infection by increasing susceptibility of the affectedcells to T