A 74-year-old male was found to be suffering from the Brugada syndrome after undergoing high dose chemotherapy followed by autologous peripheral blood stem cell transplantation (ABSCT) for acute myeloid leukemia. A specific ECG pattern of right bundle-branch block and a coved-type ST-segment elevation in leads V1 through V3, which is compatible with the Brugada syndrome, was unmasked by febrile neutropenia on the 8th day after ABSCT. He experienced syncope on the 11th day due to ventricular tachycardia, which was immediately improved with the administration of intravenous lidocaine. The Brugada syndorome should be considered in febrile patients if they have a episode of syncope or ECG change.