Liver disease is increasingly recognized as an important chronic disease worldwide because of its potential impact on the patient's health and the entire society. The impact of chronic liver disease falls into three categories: clinical, quality-of-life, and economic. The clinical impact of chronic liver disease relates to its prevalence and potential for progression. Chronic liver disease is common and is considered one of the leading causes of death in the United States. Chronic viral hepatitis and nonalcoholic fatty liver disease are quite prevalent in the United States and the rest of the world. In general, 20–25% of patients with chronic viral hepatitis and probably other chronic liver diseases can develop advanced fibrosis and cirrhosis. The disease burden for viral hepatitis is significant, with hundreds of patients dying each year from acute liver failure and thousands of others succumbing to the sequelae of chronic hepatitis and cirrhosis. In addition to viral hepatitis, other liver diseases such as nonalcoholic fatty liver disease, alcoholic cirrhosis, autoimmune liver diseases, and others result in significant mortality and morbidity. Because complications of cirrhosis can be recognized early, liver transplantation has become the standard of care treatment modality for end-stage liver disease. However, as the number of patients on the liver transplant list grows, the median waiting time for a liver transplant has increased. This increase in the number of patients listed for liver transplantation, coupled with a shortage of available organs, has resulted in an increasing number of patients dying on the transplant list.