De novo autoimmune hepatitis (AIH) occurred in patients who underwent liver transplantation for a different etiology. This 55-year-old woman was transplanted due to PBC. One year after liver transplantation, she complained of fatigue. Liver function tests showed markedly elevated serum alanine transaminase (ALT) and globulin levels. She also tested positive for anti-nuclear antibodies (ANA). Liver biopsy showed lymphocytic and plasmacytic infiltration in the portal and periportal areas, with numerous areas of bridging centrilobular necrosis, indicating AIH. She had a pretreatment AIH score of 16 points, and a posttreatment score of 18 points according to the scoring system of the International AIH Group (IAHG). The patient was treated effectively with prednisone, but then suffered two further episodes of AIH as a result of decreasing the prednisone dose. Histological features on liver biopsy were similar to those on initial presentation. Treatment with prednisone and azathioprine resulted in a dramatically improved outcome. Her liver function and globulin levels rapidly returned to normal and have remained so thereafter.