Lumbar drainage is one of the methods used to prevent the occurrence of intracranial hypertension and treatment of nasal liquorrhea in patients after by endonasal transsphenoidal endoscopic removal of tumors of the chiasmosellar region. The application of this method intraoperatively is a standard procedure to facilitate manipulation of the brain surgeon, but prolonged post-operative drainage is used extremely selectively and depending on the approaches taken in the specific medical organization. The present paper describes different frequency and risks of lumbar drainage after the surgery. Our aim was to assess the efficacy and safety of postoperative drainage of liquor from the surveyed patients. We observed 80 patients in the postoperative period who were conducted passive lumbar drainage. The assessment was performed of the cell count and discharge of the liquor, depending on the size of the tumor. During the study, it was found that the optimal timing of drainage is: 3 days for patients with small and medium-sized pituitary adenomas and 5 days for patients with large and giant adenomas. In all cases, the maximum values of cell count were observed on the first day and they gradually reduced by the 3-5th days due to reorganization of the liquor and reduced inflammatory response. Postoperative meningitis developed in 6 (5.8 %) cases and in 3 cases this complication led to death. It has been found, that prolonged liquor drainage meets the standards of safety and effectiveness for the correction of intracranial hypertension and accelerates the rehabilitation of the CSF.