Objective: To retrospectively evaluate the effectiveness of the endoscopic endonasal removal of pituitary adenomas (PAs) with paraclival internal carotid artery (ICA) invasion. Methods: Between February 2002 and August 2009, 14 consecutive patients underwent 'pure' extended endonasal transsphenoidal endoscopic surgery for PAs with paraclival ICA invasion. The clinical outcomes of the patients were evaluated, including symptoms, the extent of the tumor, the amount of tumor removed and any complications. Results: Tumor removal, as assessed by intraoperative endoscopic inspection, postoperative magnetic resonance imaging and clinical evaluation, revealed total resection (cured) in 10 out of 14 PA patients, 1 subtotal resection (controlled), and 3 partial resections (improved). Three patients had recurrences and 2 underwent re-resection. A cerebrospinal fluid leak was seen in 1 patient. There were no cases of meningitis. All of the patients who had symptoms were discharged. Conclusion: Extended endonasal transsphenoidal endoscopic surgery for PAs with paraclival ICA invasion is a safe and effective alternative procedure after proper training. Moreover, the technique is less invasive and effective and requires less time than traditionally utilized procedures. Copyright (C) 2010 S. Karger AG, Basel