Cerebrospinal fluid (CSF) leak is one of several complications that can occur after traumatic skull base injury. Although most patients present soon after the injury occurs, some can present years later, with resulting morbidity and the need for additional procedures. We present a case of a patient with a sphenoid sinus CSF leak who presented 12 years after a closed head injury that included a sphenoethmoid skull base fracture. We also reviewed the literature on this topic, with a discussion of previous reports of CSF leaks that occurred months, years, or decades after trauma. A late onset CSF leak appears to be a rare but important complication of traumatic skull base injury. This case highlights the need for clinicians to remain vigilant to the possibility of delayed CSF rhinorrhea, even years after traumatic head injury.