BACKGROUND: Herpes simplex virus (HSV) is a rare cause of acute viral hepatitis but has high mortality rates and primarily affects immunocompromised hosts. We report a case of HSV hepatitis in a 20-year-old female kidney transplant recipient who had 1000-fold elevations in transaminases on post-transplant day 14, and the strategies employed for diagnoses and treatment. METHODS: Routine laboratory, serological, and molecular viral testing was completed, and she underwent a bone marrow given initial suspicion of hemophagocytic lymphohistiocytosis (HLH). HSV serologic results and high transaminases triggered a liver biopsy. RESULTS: The patient presented with elevated transaminases (ALT 1731 U/L and AST 1400) and ferritin (1431 ug/L). Transaminases and ferritin peaked with an ALT of 6609 U/L, AST of 6525 U/L, and ferritin > 50000 ug/L. Bone marrow biopsy revealed no definitive HLH. HSV-DNA PCR of blood was positive, and she was empirically started on intravenous acyclovir 10mg/kg t.i.d. Liver biopsy confirmed the histological diagnosis of HSV hepatitis. CONCLUSIONS: Given the high mortality rates associated with HSV hepatitis, it is crucial to determine pre-transplant HSV status, initiate appropriate antiviral prophylaxis, and to have a low threshold for investigating for HSV hepatitis and initiating treatment in patients with a suspected diagnosis.