AIH, ASC, and de novo AIH after liver transplantation are childhood liver diseases of an autoimmune nature. The mode of presentation of AIH in childhood is variable, and the disease should be suspected and excluded in all children presenting with symptoms and signs of prolonged or severe acute liver disease. Although corticosteroids are effective in all types of childhood AIH, patients with LKM1 have a higher frequency of acute hepatic failure and relapse after corticosteroid withdrawal than do patients with ANA/SMA. ASC occurs commonly in the absence of inflammatory bowel disease, requires cholangiography for diagnosis, and improves during corticosteroid therapy. The development of AIH de novo in children who undergo liver transplantation for nonautoimmune liver disease may reflect interference with the maturation of T cells by immunosuppressive drugs.