Background: The management of Non-Functioning Pituitary Adenoma (NFPA) invading the cavernous sinus (CS) is currently a balancing act between the surgical decompression of neural structures, radiotherapy and a wait-and-see policy. Methods: We undertook a retrospective review of 56 cases of NFPA with CS invasion treated through an endoscopic endonasal approach (EEA) between 2000 and 2010. The Knosp classification was adopted to describe CS involvement using information from preoperative MRI and intraoperative findings. Extent of resection and surgical outcomes were evaluated on the basis of postoperative contrast-enhanced MRI. Endocrinological improvement and visual outcomes were assessed according to the most recent consensus criteria. Results: EEA was performed using direct para-septal, trans-ethmoidal-sphenoidal or trans-ethmoidal-pterygoidal-sphenoidal approach. Visual outcomes improved in 30 (81%) patients. Normalization or at least improvement of previous hypopituitarism was obtained in 55% of cases. A gross total resection was achieved in 30.3% of cases. The recurrence-free survival was 87.5%, with a mean follow-up of 61 months (range, 36-166 months). No major intraoperative or postoperative complications occurred. Discussion: EEA is a minimally-invasive, safe and effective procedure for the management of NFPA invading the CS. The extent of CS involvement was the main factor limiting the degree of tumor resection. The EEA was able to resolve the mass effect, preserving or restoring visual function, and obtaining adequate long-term tumor control.