Five patients with cerebrospinal fluid fistula (CFF) have been treated with intratecal fluoresceine, 2 cc at 2%, and endoscopic nasal surgery. In 3 patients CFF was postraumatic; one case spontaneous and another case iatrogenic. In all the cases CFF have been solved in the first time. Postoperatory follow-up vary from 8 to 14 months, and no recurrence was observed. Fluorescein must be managed adequately for prevent neural complications.