Prior radiation to the nasopharynx or paranasal sinuses is a risk factor for flap necrosis, while septal spurs and iatrogenic injury can lead to intra operative injury of the flap Post operative CSF leak after reconstruction of the anterior skull base defect using NSF was minimal regarding to other techniques and even if occurred can be treated by endoscopic surgery again. The NSF should be considered as the first line of treatment after transnasal endoscopic skull base resections.