As our understanding of the natural history of hepatitis B virus (HBV) infection increases, so do the patient circumstances for which anti-HBV therapy is considered. For example, patients with chronic HBV infection that is negative for hepatitis B surface antigen can experience hepatitis flares during or after cytotoxic chemotherapy and thus are potential candidates for anti-HBV therapy. Also, although passive-active immunoprophylaxis is highly effective in preventing the vertical transmission of HBV, high maternal serum HBV DNA concentrations have been associated with the failure of immunoprophylaxis; for this reason, clinicians may consider administering anti-HBV therapy during pregnancy. However, prophylactic anti-HBV therapy can be both complex and controversial. A satellite symposium conducted during the 57th Annual Meeting of the American Association for the Study of Liver Diseases (AASLD) in Boston, Massachusetts, presented approaches to treating HBV infection in patients who are pregnant and in those who are preparing to receive chemotherapy.