Chronic hepatitis B virus (HBV) infection affects 350 million people worldwide and 25-30% of these individuals will die as a result of their infection mainly as a results of hepatocellular carcinoma HCC. Liver cirrhosis, high viral load and dietary exposure to aflatoxin are recognised as risk factors for hepatocellular carcinoma amongst HBV carriers. However, these variables do not account for all cases of HCC and decompensated cirrhosis is rarely ever seen in West Africa suggesting that advanced liver fibrosis may not be an important risk factor in this population. A large case control study on HCC will be used to evaluate the importance of liver fibrosis and other established risk factors in West Africa and to explore other potential oncogenic determinants. The case-control study will generate serum, urine and DNA samples for proteomic, metabonomic and genomic analysis to identify biomarkers and aetiological agents for HCC. Effective treatment for HBV infection is now available in the developed world but treatment programmes have not been developed for resource poor settings even though some of the effective medication is now available at low cost for HIV management. A trial of HBV treatment in a group of carefully selected high risk patients will be conducted to demonstrate that the incidence of HCC can be reduced in this population as has been observed in Asian patients. The treatment trial will also be used to evaluate the efficacy of screening by ultrasound for early tumours which can be treated with percutaneous alcohol injection. This comprehensive programme therefore aims to reveal novel aetiological factors for HCC, identify and evaluate biomarkers and demonstrate the efficacy of selective antiviral therapy to prevent HCC