Cerebrospinal fluid leak represents a frequent complication in Craniopharyngioma´s Endoscopic Endonasal Approach. A descriptive observational investigation was performed in 50 adult patients operated of Craniopharyngiomas by aggressive Expanded Endonasal Endoscopic Approach (EEEA) in “Hermanos Ameijeiras” Hospital since 2010 to 2019 using nasoseptal flap. The 14% of all patients develop CSF leak and 85,7 % of these cases had a great communication into third ventricle creating a cisternoventricular space. Was identified relation with tumor size, hypothalamic invasion and adhesion strength of tumour. Surgical cavity suffered hydrostatic and hydrodynamic pression than lead to CSF leak independent of multilayer reparation.