We report the case of a 40-year-old female patient admitted at our clinic because of recent onset jaundice and elevated transaminases. Two months before admission the patient had unprotected sexual contact with a potential hepatitis B-infected man. Virological screening performed in our clinic revealed IgM antibodies against hepatitis B virus core protein (anti-HBc-IgM) and elevated HBV-DNA. Our first diagnosis was an acute hepatitis B virus infection. During her stay at our clinic the patient achieved HBe seroconversion and a loss of HBV-DNA. Nevertheless the transaminases remained high and jaundice persisted. The histological examination of the liver biopsy showed interface hepatitis with plasma cells as the characteristic signs of autoimmune hepatitis. On that basis we started an immunosuppressive therapy with prednisolone in parallel with a prophylactic lamivudine therapy and after two weeks there was a complete resolution of jaundice and a normalisation of transaminases. In conclusion, we present a rare case report of an autoimmune hepatitis as a result a newly acquired hepatitis B infection. This case report highlights the relationship between viral infection and autoimmunity within the liver.