Giant cell hepatitis is a well-known histological feature of several neonatal and infantile liver diseases. In contrast, postinfantile giant cell hepatitis is rarely identified in adult liver biopsies. It has been associated with varying etiologies, mainly viral infections, drug toxicity, and autoimmunity. Here, we report an 18-year-old, previously healthy man with acute liver failure, who showed giant cell hepatitis in a liver biopsy. There was no evidence of viral hepatitis A–E, autoimmunity, and no drug history. Diagnostic work-up revealed Wilson’s disease as the underlying disease. As syncytial giant cell formation is thought to be a uniform reaction pattern not related to any specific etiology, copper toxicity in Wilson’s disease might cause giant cell formation. In contrast, our patient recalled a recent cytomegalovirus infection, which was confirmed serologically. Therefore, the giant cell formation might also be a fingerprint of an intercurrent cytomegalovirus infection as the common trigger for both giant cell hepatitis and decompensation of Wilson’s disease.