Acute on chronic liver failure(ACLF) was first described in 1995 as a clinical syndrome distinct to classic acute decompensation.Characterized by complications of decompensation,ACLF occurs on a background of chronic liver dysfunction and is associated with high rates of organ failure and significant short-term mortality estimated between45%and 90%.Despite the clinical relevance of the condition,it still remains largely undefined with continued disagreement regarding its precise etiological factors,clinical course,prognostic criteria and management pathways.It is concerning that,despite our relative lack of understanding of the condition,the burden of ACLF among cirrhotic patients remains significant with an estimated prevalence of 30.9%.This paper highlights our current understanding of ACLF,including its etiology,diagnostic and prognostic criteria and pathophysiology.It is evident that further refinement of the ACLF classification system is required in order to detect high-risk patients and improve short-term mortality rates.The field of metabolomics certainly warrants investigation to enhance diagnostic and prognostic parameters,while the use of granulocyte-colony stimulating factor is a promising future therapeutic intervention for patients with ACLF. Acute on chronic liver failure (ACLF) was first described in 1995 as a clinical syndrome distinct to classic acute decompensation. Characterized by complications of decompensation, ACLF occurs in a background of chronic liver dysfunction and is associated with high rates of organ failure and significant short -term mortality estimated between 45% and 90% .Despite the clinical relevance of the condition, it still remains largely undefined with continued disagreement concerning its precise etiological factors, clinical course, prognostic criteria and management pathways. It is concerning that, despite our relative lack of understanding of the condition, the burden of ACLF among cirrhotic patients remains significant with an estimated prevalence of 30.9%. This paper highlights our current understanding of ACLF, and its its etiology, diagnostic and prognostic criteria and pathophysiology. It is evident that further refinement of the ACLF classification system is required in order to detect high-risk patie nts and improve short-term mortality rates. the field of metabolomics certainly warrants investigation to enhance diagnostic and prognostic parameters, while the use of granulocyte-colony stimulating factor is a future future therapeutic intervention for patients with ACLF.