Abstract: Peptides are used to define epitopes that stimulate HLA-restricted cytotoxic T lymphocyte activity against hepatitis B virus antigens. The peptides are derived from regions of HBV nucleocapsid, envelope, polymerase and the transcriptional transactivator X protein, and are particularly useful in treating or preventing HBV infection, including methods for stimulating the immune response of chronically infected individuals to respond to HBV antigens. Pharmaceutical compositions and hepatitis B vaccines which comprise the peptides and physiologically acceptable carriers can be employed in conjunction with other HBV vaccines to provide more effective immunity against the disease. Methods for identifying individuals who are particularly susceptible to developing chronic HBV infection and who can be targeted for treatment by the CTL peptides are also provided.