Hepatitis A virus (HAV) is the most common cause of acute viral hepatitis in the world. Rarely, acute infection may persist for a long time. Autoimmune hepatitis (AIH) may provide anti-HAV IgM positivity detection for a prolonged time. On the other hand, HAV as an infectious agent may also trigger AIH. Here we presented a case which seemed like a simple acute viral hepatitis A infection at the beginning but turned out to be an AIH according to the International Autoimmune Hepatitis Group's system. A 21-year-old female was diagnosed as symptomatic acute HAV infection with anti-HAV IgM positivity and elevated aminotransferase levels. The other viral serological tests were negative. On the 6(th), 12(th) and 18(th) months of the follow up, her anti-HAV IgM positivity still continued and transaminase levels were also 3 to 7 times high of the upper limit of normal. In addition, antinuclear antibody was positive. However, on the 19(th) month anti-HAV IgM could be detected as negative. Liver histology was prominent. The patient had a score of 16 according to the International Autoimmune Hepatitis Group's system. She was given prednisolone (10 mg/day) and azathioprine (100 mg/day). The aminotransferase levels were detected within normal ranges at the end of the first month of therapy. She was in remission during follow up for 6 years. In conclusion, prolonged HAV infection and AIH may not only trigger each other but also deteriorate the liver histology. AIH should be investigated in cases of long-lasting HAV infection in order to begin the treatment earlier. On the other hand, AIH patients should also be vaccinated for both HBV and HAV to avoid more severe diseases.