Primary spontaneous cerebral spinal fluid (CSF) rhinorrhoea is a rare disease associated with female gender, obesity and empty sella syndrome. The authors describe the case of a 59-year-old woman who presented to her primary care physician with a 2-week history of drainage of a clear fluid from her right nostril that was initially treated as allergic rhinitis. A non-contrast CT scan revealed mucosal thickening in the right sphenoid sinus and a possible defect in the adjacent skull base. The patient initially declined a CT cisternogram, which provides greater sensitivity in assessing for a CSF leak. Nasal secretions tested positive for β-2-transferrin, which is highly sensitive and specific for CSF. After conservative interventions failed, a pedicled septal mucoperichondrial flap was used to patch the skeletal defect. At her 5-month follow-up, the patient remains asymptomatic.