Abstract
Patients with current or past hepatitis B virus (HBV) infection are at risk of viral reactivation if they receive immune-modulating treatment or chemotherapy. This can range from subclinical elevation in HBV DNA levels, to abnormal liver function tests, to severe hepatitis with liver failure and risk of death. All patients should be screened for hepatitis B with surface antigen and core antibody before receiving immunosuppression. Patients with positive hepatitis B serology should be referred for specialist advice. Prophylactic antiviral treatment is recommended for patients with current/past hepatitis B who receive immunosuppressive chemotherapy.