This is a general clinical research protocol to allow for evaluation, investigation and long-term follow up of patients who have an acute or chronic liver disease. The protocol is designed to study the natural history and pathogenesis of various liver diseases such as acute and chronic hepatitis B, C, D and E, primary biliary cirrhosis, primary sclerosing cholangitis, Wilson's disease, hemochromatosis, nonalcoholic steatohepatitis (NASH), noncirrhotic portal hypertension, hepatocellular carcinoma, and cryptogenic or poorly defined forms of chronic liver disease. Patients will initially be seen in the outpatient department and undergo a medical history and physical examination. They will have a series of blood and urine tests and abdominal ultrasound. Patients will then be followed in the outpatient department at intervals appropriate for their clinical status, at which times they will undergo an interim medical history and brief examination and have blood studies taken. Liver biopsies will be done as a part of this protocol only if clinically indicated. In addition, patients may be asked to undergo skin biopsy, plasmapheresis, lymphapheresis, genetic analysis, and Fibroscan procedures for research purposes only (immunologic, virologic, genetic, and other studies) and separate consent forms are provided. Patients qualifying for therapeutic or other trials of antiviral or immunomodulatory agents for their liver disease will be invited to enter such studies.