A 38-year-old woman presented with a case of post-traumatic ethmoidal cerebrospinal fluid (CSF) leak that was repaired using a purely endoscopic endonasal approach. Six weeks after a mild domestic maxillofacial trauma, she started complaining of clear, watery discharge from the left nostril and headache. Neuroimaging investigations disclosed a linear fracture of the left anterior ethmoidal roof without evidence of large bony breaches or any brain tissue damage. After conservative medical treatment with carbonic anhydrase inhibitors failed, she was referred to our hospital for surgical repair of the osteodural defect. An endoscopic endonasal transethmoidal approach was successfully performed, and an overlay technique was used to reconstruct the defect. The patient was discharged without clinical evidence of CSF rhinorrhea and no leaks were apparent at the 3-month follow-up clinical and radiological examinations. Post-traumatic CSF rhinorrhea occurs in cases of dural tears associated with small bone breaks, most frequently involving the anterior skull base. Recovery is often spontaneous following only bed rest, or with medical treatments such as inhibitors of carbonic anhydrase diuretics, steroids, or eventually stool softeners to help reduce CSF pressure. Surgical repair is required when first-line conservative treatment proves ineffective. The present case shows that the endoscopic endonasal technique for the management of CSF leaks provides a less invasive surgical route to achieve valid dural repair.