Autoimmune hepatitis (AIH) is a chronic and progressive liver disease characterized by histological interface hepatitis and circulating autoantibodies. Our aims were to evaluate risk factors that contribute to the outcome and, particularly, the development of liver cirrhosis in a prospective multicenter cohort study of AIH. One hundred and seventy-four patients were enrolled. Histologically 21 (12.1%) had cirrhosis at the initial observation and the remaining 153 showed chronic or acute hepatitis at presentation. Among the latter 153 patients, 14 developed cirrhosis during the follow-up period (mean 8.0 years). Demographic, clinical, and laboratory indices associated with the development of cirrhosis were identified. Patients who developed cirrhosis differed in mean levels of alanine aminotransferase (ALT; 158 ± 182 vs. 441 ± 423 IU/ml) and platelet counts (14.7 ± 5.5 vs. 19.4 ± 6.9 × 10(4)/μl) at presentation and received lower doses of corticosteroid (13.9 ± 15.8 vs. 31.8 ± 85.5 mg/day). In a multivariate analysis, an independent predictor for progression to cirrhosis was an older age of onset (≥ 60 years). AIH patients with cirrhosis, or those who developed cirrhosis, had a worse survival. AIH patients with an older age of onset were likely to develop cirrhosis, and careful observation and aggressive treatments are necessary for such patients.