Chronic liver disease and cirrhosis, a common end result of viral hepatitis, alcohol abuse, and the emerging epidemic of nonalcoholic fatty liver disease are a significant source of morbidity and premature mortality globally. Acute clinical deterioration of chronic liver disease exemplifies the pinnacle of healthcare burden due to the intensive medical needs and high mortality risk. Although a uniformly accepted definition for epidemiological studies is lacking, acute-on-chronic liver failure (ACLF) is increasingly recognized as an important source of disease burden. At least in the United States, hospitalizations for ACLF have increased several fold in the last decade and have a high fatality rate. Acute-on-chronic liver failure incurs extremely high costs, exceeding the yearly costs of inpatient management of other common medical conditions. Although further epidemiological data are needed to better understand the true impact and future trends of ACLF, these data point to the urgency in the clinical investigation for ACLF and the deployment of healthcare resources for timely and effective interventions in affected patients.