Worldwide, hepatitis B virus (HBV) is the most common among those hepatitis viruses that cause chronic refections of the liver in humans, and it represents a global public health problem. Chronic hepatitis caused by HBV is the major cause of hepatocellulax carcinoma (HCC) worldwide, and remains therefore a major public health problem globally. This fact is related to both the continuing occurrence of frequent new refections and to the presence of a large reservoir of persons chronically infected, which may develop severe and fatal complications of chronic liver disease. Hepatitis B and all of the complications resulting from it, as well hepatitis D (HDV) and its complications, are globally preventable by hepatitis B vaccination, and therefore elimination of HBV transmission and of new acute and chronic infections is a feasible goal. (C) 2005 Elsevier B.V. All rights reserved.