Cerebrospinal fluid (CSF) leakage is a major complication after extended endonasal transsphenoidal surgery (EETSS), which is commonly used in the treatment of anterior skull base tumors. Dural suturing and graded reconstruction are promising techniques to further decrease the incidence of postoperative CSF (poCSF) leakage. The effect of continuous dural suturing in endoscopic surgery was investigated in this retrospective study. A total of 79 EETSS patients were included; the procedures were performed for subdural tumor removal by a single endoscopic neurosurgical team. Comparisons were applied between patients who did and did not undergo endoscopic dural suturing after tumor removal. Multivariate logistic regression analysis was performed to identify variables that significantly influenced the incidence of poCSF leakage. In all, 79 adult patients developed Esposito’s grade 3 intraoperative high-flow CSF leakage. Ten patients (12.7%) experienced poCSF leakage. One of the 36 patients who underwent intraoperative dural suturing developed poCSF leakage, compared with nine of 43 patients who did not undergo dural suturing (p = 0.016). Regression analysis showed that dural suturing could significantly decrease the incidence of poCSF leakage (p = 0.049, OR 0.108, 95% CI 0.013–0.899). Prophylactic lumbar drainage could also help decrease the CSF leakage rate. Dural suturing under endoscopy is a promising and effective method for application in skull base reconstruction after subdural skull base tumor removal. With future progress, lumbar drainage and even nasoseptal flap placement could be replaced in certain groups of patients undergoing EETSS. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.