Spontaneous nasal liquorrhea is a pathological condition associated with defects between the nasal cavity and the intracranial structures, which results in CSF leak from the nasal cavity. Diagnostic criteria include: anamnesis, examination of the nasal fluid, endoscopic examination of the nasal cavity, and CT-and MRI-cisternography. Conservative therapy is applicable to small fistulas. In the case of the inefficiency of this method, surgical method is then applied to the defect closure. Purpose of the study: To evaluate the effectiveness of endoscopic endonasal approach in the CSF leak treatment. Materials and methods: For the period from 2008 to 2018 at the Pavlov First Saint Petersburg State Medical University, at the clinic of neurosurgery of the Kirov Medical Institute and the Medical Research Center Almazov, 38 patients with spontaneous nasal liquorrhea were treated. All patients underwent plastic surgery of the CSF fistula by endoscopic endonasal approach. Results: In 4 cases, there was a large defect requiring secondary surgical intervention 1-2 weeks after the initial operation. Conclusions: The use of auto tissues (muscle or fat) is the method of choice for repeated surgical plastics of the cerebrospinal fluid fistula or in the case of a large size defect.