Hepatitis B virus is the second most common cause of cancer behind tobacco with almost 1 million deaths per annum from liver cancer. The precise changes in the virus which trigger the development of liver cancer later in life are unknown. The aim of this study is to try to identify these changes by analysing the entire HBV DNA in samples taken in 1984 from 572 young Maori in the Kawerau study, a number of whom have since developed liver cancer. These 1984 blood samples will be analysed by the very sensitive technique of next generation whole genomic sequencing. All HBV sequences from all patients will be then analysed by powerful software programme to identify specific mutations or deletions in the HBV genome which are associated with liver cancer development. Any such marker could then be used to predict someone’s life-long risk for liver cancer and need for surveillance.