Introduction - The natural history of viral cirrhosis remains poorly understood. The ANRS CO12 CirVir cohort aims to improve this understanding and identify predictors of complications. Methods - Patients are enrolled if they have histologically confirmed cirrhosis, positive serum anti-HCV antibodies and/or HBsAg, and no complications. A biobank of biological samples is being established. The target final enrollment is 3,000 patients. Results - The 36 participating centers have currently enrolled 917 patients. The results pertain to the first 774 patients: 80% have HCV-related cirrhosis and 18.5% have HBV-related cirrhosis. Patients with B-cirrhosis are younger (52.6 years vs. 57.6 years), more often male (83% vs. 64%), and have a lower prevalence of excessive alcohol consumption and dysmetabolic steatohepatitis (5% vs. 18%). Events already reported include hepatocellular carcinoma (n=11), bacterial infection (n=10), and decompensated cirrhosis (n=3). Discussion and Conclusion - A separate analysis of the clinical course of patients with B and C cirrhosis will help determine whether there are differences in the nature and incidence of complications, and identify specific predictive factors for each etiology. (R.A.)