Reactivation of hepatitis B virus replication is a known complication of immunosuppressive therapy, which can lead to hepatocellular injury, liver failure, and death. In this report, we describe the case of a 44-year-old man with chronic hepatitis B and a dilated cardiomyopathy status after a heart transplant. Reactivation of the patient 's hepatitis B virus occurred 4 months after the heart transplant. Despite prompt administration of antiviral therapy, he developed fulminant hepatitis with hepatic encephalopathy. A successful living-related liver transplant was performed 7 months after the heart transplant. The patient was followed up for 1 year, and during that time was free of hepatitis B virus. We suggest that routine antiviral therapy should be administered to patients with chronic hepatitis B receiving immunosuppressive therapy.