Cerebrospinal fluid leak in the patients without a history of trauma, surgery, malformation, tumor, or radiotherapy is known as spontaneous cerebrospinal fluid leak. The present report introduces a patient that was hospitalized due to a three-month rhinorrhea of cerebrospinal fluid. The patient was an elderly 65-year-old woman with obesity who had been referred to the clinic since three months ago because of intermittent nasal rhinorrhea. The patient did not have any history of trauma to the head or hypertension. The patient was initially treated due to allergic rhinitis diagnosis, however, no improvement was observed. The patient then had referred to the neurological clinic for headache, and antibiotic treatment was started for her due to sinusitis diagnosis, but as the headache was not resolved, she had received various treatments in the later stages of referrals due to other diagnoses. During the referral, the patient was also complaining of headache besides rhinorrhea. Examinations at the time of referral were normal. The patient did not mention the history of any certain diseases and did not consume any special medications before the onset of symptoms. A beta-2 transferrin test was requested for the patient, which was positive. The patient also underwent CT scan of paranasal sinuses, according to it, in the coronal and sagittal views, defect was observed in the base of skull and in the sphenoid sinus region. The sella turcica was full of air and there was evidence of pneumocephalus. The patient eventually underwent surgery. Currently, according to follow-ups, the patient has a good general health and her headache and rhinorrhea are resolved. Finally, it should be mentioned that treatment of cerebrospinal fluid leak is associated with significant surgical complications. The importance of this matter is much more because of specific anatomical structure as well as various variations of the sphenoid sinus.