We report the case of a child who had deterioration of hepatic function 3 days after suffering a depressed compound skull fracture with underlying brain contusion. An abdominal enhanced CT scan revealed a wedge-shaped region of devitalised liver with associated free intraperitoneal fluid, consistent with a traumatic lesion but due to necrosis secondary to acetaminophen toxicity. Acetaminophen toxicity may occur with therapeutic doses in the presence of an ischaemic hepatitis. Any delay in the performance of CT from the time of trauma should prompt the consideration of alternative diagnoses.