Polyarteritis nodosa is a systemic necrotizing vasculitis that affects small- and medium-sized arteries. Liver involvement in patients with polyarteritis nodosa has been described, and ranges from asymptomatic elevation of aminotransferases to hepatic aneurysm rupture. We describe the case of a patient with type 1 autoimmune hepatitis and compensated liver cirrhosis who developed classic polyarteritis nodosa, complicated with cytomegalovirus and repeated urinary tract infections. After a long bedridden hospitalization, the patient's condition was stabilized. She is currently in good health, with well-controlled blood pressure, and stable kidney and liver function. To our knowledge, this is the first case report in the literature with concurrent appearance of both diseases.