DNA of individual cirrhotic nodules (CN) and hepatocellular carcinoma nodules (HCN) of three hepatitis B surface antigen positive autopsy cases with macronodular cirrhosis were analyzed by Southern blot and slot blot hybridization with a hepatitis B virus (HBV) DNA probe. Evidence of episomal or replicating viral DNA, viral DNA integration at the same cellular DNA site in many cells (clonal integration) and viral integration in different cellular DNA sites in many different cells (non-clonal integration) was found in different cirrhotic nodules of the same liver, indicating heterogeneity in the state of HBV in different cells and in different cirrhotic nodules within each infected liver. Episomal or replicating viral DNA forms were found in all cirrhotic nodules of one liver, in less than 10% of examined nodules of a second liver and in none of the third. Evidence of clonal viral integration was found in CN of all three livers and non-clonal integration in CN of the latter two. Cirrhotic nodules with apparent different integrations in many different cells (non-clonal integration) outnumbered those with the same integration site in many cells (clonal integration), and many cirrhotic nodules in those two livers had no detectable viral DNA. Cirrhotic nodules with a viral integration in the same cellular DNA site in many cells would appear to have been formed by clonal expansion of an original cell containing the viral integration, and cirrhotic nodules with different integrations in many different cells (non-clonal integration) may have been formed by recruitment of many different cells with different viral integrations or by clonal expansion of cells without HBV integrations and subsequent viral integrations occurring integration. In one liver, three different hepatocellular carcinoma nodules appeared to represent metastatic lesions because the clonal pattern of HBV integration was identical in each, and in another liver different HCN appeared to be of different clonal origin, i.e. to have arisen from different cells, because multiple viral integrations (i.e. multiple individual restriction fragments with HBV sequences) were each different in different HCN of that liver.