Hepatitis B is one of the most common infectious diseases in the world. It has been estimated that 350 million people worldwide are chronic hepatitis B virus (HBV) carriers. The global prevalence of chronic HBV infection varies widely, from high ( > 8%, e.g., Africa, Asia and the Western Pacific) to intermediate (2-7% e.g., Southern and Eastern Europe) and low (< 2%, e.g., Western Europe, North America and Australia). The predominant routes of transmission vary according to the endemicity of the HBV infection. In areas of high endemicity, perinatal transmission is the main route of transmission, whereas in areas of low endemicity, sexual contact amongst high-risk adults is predominant. Between one-third and one-quarter of people infected chronically with HBV are expected to develop progressive liver disease (including cirrhosis and primary liver cancer). Although mass vaccination programs have begun to control the spread of HBV infection, therapeutic intervention is the only option for those with established chronic HBV-associated liver disease. Until recently, the only treatment for chronic hepatitis B was the immune modulator, interferon (IFN) alpha. However, IFN alpha treatment has several disadvantages; it is expensive, it must be administered by injection, there are side-effects, and IFN alpha is poorly tolerated. Lamivudine, a nucleoside analogue, is the first effective, and well tolerated, oral treatment for chronic hepatitis B. In conclusion, although we are still some way from eradicating or curing chronic hepatitis B, the advent of lamivudine allows new populations to benefit from therapy and helps to address the global public health problem of hepatitis B.