Hepatitis B virus (HBV) infection is the one of the most common causes of the liver diseases in Korea. Since the discovery of Australia antigen (hepatitis associated antigen, or HBsAg later), hepatitis associated antigen was tested widely. HBsAg was detected in 6.6-8.6% in 1980's. Later, it decreased to 5.7% in 1990's. Remarkably, seropositivity of the children deceased to 0.2% after the nationwide vaccination program. Although hepatitis B vaccines are highly effective, the failure rate of perinatal prophylaxis in babies born to HBsAg positive mother was reported to be 4.25%. Treatment of chronic hepatitis B was initiated after the introduction of interferon alpha. Lamivudine opened a new era of oral antiviral agent, and it has been widely used in Korea since 1999. Adefovir was proven to have a good efficacy for lamivudine-resistant chronic hepatitis B. Newer potent antiviral agents such as entecavir, clevudine, and telbivudine are available currently. Further studies are warranted for understanding factors influencing natural history, improving treatment outcomes, and overcoming vaccine non-response.