Aim: We aimed to identify the risk factors associated with intra- and postoperative cerebrospinal fluid leakage in pituitary adenomas treated by endoscopic transsphenoidal surgery. Material and methods: A retrospective analysis of 250 pituitary adenoma cases from January 2017 to December 2019 at our hospital was conducted; all patients underwent endoscopic endonasal transsphenoidal surgeries. A univariate analysis and multivariate analysis was performed to investigate the risk factors associated with intra- and postoperative CSF rhinorrhea.Results: Eighty(32.0%) and nine(3.6%) patients had intraoperative and postoperative CSF leakages, respectively. Tumor size was an independent risk factor for intraoperative CSF leakage (OR, 1.229; 95% CI, 1.133–1.334; P<0.001); intraoperative CSF leakage was an independent risk factor for postoperative CSF leakage (OR, 7.707; 95% CI, 1.336–44.455; P=0.022). Chronic respiratory disease (OR, 57.500; 95% CI, 8.031–411.682; P<0.001) was also an independent risk factor for postoperative CSF leakage; vascularized septal mucosal flap was a protective factor for such (OR, 0.107; 95% CI, 0.013–0.894; P=0.039).Conclusion: Intraoperative CSF leakages are more likely to occur in large pituitary adenomas; in the presence of intraoperative CSF leakages, postoperative CSF rhinorrhea is very likely to occur. Patients with chronic respiratory disease are also more likely to develop postoperative CSF leakages. However, the sellar base reconstructed using vascularized nasal septal flaps can significant decrease the risk for such. Knosp grade, degree of tumor resection, postoperative lumbar subarachnoid drain use did not seem to have effect on the postoperative CSF rhinorrhea.