New immunosuppressive and antineoplastic drugs are becoming both more numerous and more widely used, even during several years. Most of them present a low-moderate risk of hepatitis B virus (HBV) reactivation in HBsAg-negative and anti-HBc-positive patients. However, their reactivation capacity has not been clearly studied. We present the clinical case of a patient with these serological characteristics who, after 5 years of treatment with ibrutinib for chronic lymphocytic leukaemia, developed VHB reactivation, which was controlled with tenofovir. The occurrence of this event with drugs such as ibrutinib may lead to changes in HBV reactivation prophylaxis.