A 46-year-old woman presented with arthralgia. She had a history of fluctuating liver function impairment for 6 months. Laboratory investigations revealed elevated liver function test results, positive antinuclear antibodies and elevated serum IgG. The histological findings of a liver biopsy were interface hepatitis accompanied by plasmocytic infiltration with bridging fibrosis. There was no evidence of cirrhosis on pathological examination and no portal hypertension on endoscopic and radiographic studies. Autoimmune hepatitis was diagnosed, and treatment with prednisolone improved the liver dysfunction. After 6 months, she complained of dyspnea. Doppler echocardiography showed a dilated right ventricle, severe tricuspid insufficiency, and systolic pulmonary arterial pressure indicative of pulmonary arterial hypertension. We report this rare case of autoimmune hepatitis with pulmonary arterial hypertension.