The hepatitis B virus transcripts in human hepatoma and its adjacent nontumorous liver were examined with probes specific to hepatitis B virus surface antigen, core antigen, X region and pre-S region. The study shows that the patterns of hepatitis B virus transcripts for tumorous tissue and the counterpart in nontumorous liver differ. In most of the tissues examined, the surface antigen gene is transcribed. Most of these transcripts, besides having surface antigen sequences, also have an X region; some also include a pre-S region. The transcripts that hybridized to a core-specific probe were a pair of poly(A+) RNA, 3.5 and 2.2 kilobases in size, present in two of the nontumorous hepatocytes where the virus was actively replicating. The 3.5-kilobase transcript not only hybridized to the core probe, but was able to be hybridized to other hepatitis B virus subgenomic probes and might represent the RNA pregenome involving hepatitis B virus DNA replication. Whereas most of the transcripts hybridizable to hepatitis B virus probe are in the size range of 2.1 to 2.7 kilobases, some transcripts other than the pregenomic RNA appear to be greater than 3.2 kilobases in size and may represent the hybrid RNAs of viral and host sequences.