Autoimmune hepatitis is one of the causes of chronic progressive liver disease in childhood. Here we report 14 cases with clinical findings, therapeutic management and prognosis, in order to define the course of the disease. Diagnosis of autoimmune hepatitis was done with the presence of at least one of these autoantibodies; antinuclear antibody, smooth muscle antibody, liver-kidney microsomal type 1 antibody, and perinuclear antineutrophilic cytoplasmic antibody. Patients were seen every 3 to 6 months. After doing a complete physical examination, biochemical parameters and autoantibodies determined at each visit. Mean age at diagnosis was 10.9 +/- 2.6 years (range, 7-15.5 years) and female to male ratio was 1:3. Thirteen patients had jaundice and all had high levels of ALT, AST and gammaglobulin. Hepatomegaly was found in 71.4% and splenomegaly in 64.3% of the patients. All patients were classified as type 1 autoimmune hepatitis. Liver biopsies revealed severe active hepatitis with mononuclear cell infiltration in portal areas, piecemeal necrosis. Drug therapy consisted of prednisone (2 mg/kg/day) per oral at the beginning, and addition of azathioprine (1.5 mg/kg/day) per oral at the 3rd-6th month with slow tapering of prednisone in 12 children. Both drugs were started together to two patients. Follow-up period was 30.7 +/- 15.6 months (range, 12-72 months). Sustained normalization of ALT could not be obtained with tapering doses of prednisone alone. Decrease in ALT levels did not correlate with disappearance of serum autoantibodies. None of the patients showed decompensation of liver disease. Azathioprine administration is necessary to decrease prednisone dose and to maintain a sustained normal transaminase values.