The purpose of the study is to evaluate the outcome and to determine predictive factors of patients admitted in a context of acute liver failure without identified cause.

Methodology: Multicentric French national cohort with prospective collection of data and constitution of biobank, in patients hospitalized in a context of acute liver failure without known cause at admission. Follow-up during 3 months for each patients. The primary objective is to determine predictive factors of early mortality. This study is an observational cohort and patients will received standard care during the follow-up.

Inclusion Criteria:

• Acute liver failure defined by a PT<50% or INR>1.5;
• with or without hepatic encephalopathy;
• without cause identified at admission, and non A non B hepatitis;
• age>18 year old;
• signed an informed consent.

Exclusion Criteria:

• chronic liver disease;
• Patient under guardianship

Acute liver failure without cause identified at admission