It is estimated that approximately 2 billion people in the world are either currently infected or have previously been infected with the hepatitis B virus (HBV), making it the most common viral infection in the world. HBV infection has a variety of possible clinical sequelae, including active hepatitis, liver failure, cirrhosis and liver cancer, some of which can be fatal. HBV infection is often difficult to diagnose and no specific treatments are available. Therefore, prophylactic vaccination plays an important role in preventing disease transmission. Hepatitis B vaccines became commercially available within the last 15 years and most consist of formulations of HBV surface antigen (HBsAg). First generation vaccines contained plasma-derived HbsAg but their use was largely superseded by second generation vaccines containing recombinant HbsAg; the latter vaccines are safer and cheaper to manufacture. Several studies presented at the 9th International Congress on Infectious Diseases (ICID) [Buenos Aires, Argentina; April 2000] examined the effects of vaccination with a number of different recombinant hepatitis B vaccines.