Two patients undergoing liver transplantation for classical end-stage primary biliary cirrhosis (PBC) are described, who went on to develop de novo autoimmune hepatitis (AIH) in the transplanted liver. The presentation, in both instances, was with malaise and lethargy. Markedly elevated serum transaminases were found, together with a raised serum IgG and/or globulin fraction and histological features on liver biopsy typical of AIH. Both cases had had changes in their immunosuppressive therapy before the onset of AIH episodes, and both rapidly responded to reinstitution of steroid therapy. The finding, in each case, of a coincidental multiple HLA class I allele match between the recipient and their liver donor suggests that HLA class I-restricted mechanisms may play an important role in the pathogenesis of AIH.