Autoimmune hepatitis may be frequently associated with chronic hepatitis C (HCV) infection, but there are few case reports regarding hepatitis B and Delta infection (HBV+HDV) as possible triggers. In this report, we present a 44 years old man who was diagnosed as autoimmune hepatitis (AIH) following the treatment of HBV+HDV hepatitis with pegylated interferon (PegIFN). He presented with complaint of fatigue. Laboratory indicated elevated liver enzymes, AST 64 IU/L and ALT 112 IU/L. The results revealed HBsAg and anti-delta antibody positivity. HBV-DNA was <31.6 IU/mL and HDV-RNA 487.300 copy/mL. Peg-IFN was initiated for 96 weeks. Without a serious adverse effect, the enzymes regressed to normal within 24 weeks. After 96 weeks of treatment, there was a three-fold increase in aminotransferases, with no cholestasis. Immunoglobulin-G (IgG) was 3686 mg/dL (reference 540-1822 mg/dL), anti-smooth muscle antibody (ASMA) and anti-nuclear antibody (ANA) were positive. The liver biopsy had all diagnostic clues for AIH. Methylprednisolone and azathioprine treatment was initiated with tenofovir (TdF) prophylaxis. Due to unresponsiveness, even with doubling the dosage for immunosuppressives, treatment was stopped and shifted to mycophenolate mofetil. The patient responded in the 6th month and still under treatment with TdF and mycophenolate mofetil with normal enzymes and negative HDV RNA.