Despite the progress in minimally invasive techniques in endoscopic sinus surgery and neurosurgery, tumors beyond the sphenoid sinus and the sella have generally been considered to be too risky to be approached transnasally. The new endoneurosurgery, in combination with intraoperative MRI, is a minimally invasive surgical concept that allows the removal of tumors of the anterior skull base, the sella, and the clivus by a single transnasal approach. Our presentation aims to illustrate the potential of this concept based on our experience. Forty-eight patients with extensive tumors were operated according to this concept from January 2005 to June 2006. Technical setting comprises a microscope, endoscopes, image guidance, and intraoperative MRI. Patients were categorized according to the applied approach into group A (19 patients; transcribriform approach), B (26 patients; trans-sphenoidal approach) and C (3 patients; transclival approach). The application of these tools for neurosurgeons and otorhinolaryngologists allows resection of even extensive tumors with curative intention, avoiding secondary transcranial approach. According to our experience, tumors with compression of the third ventricle and brainstem can be resected transnasally in a single-stage operation and with relatively low risks. Patient selection for such an endoneurosurgical intervention must be based on perfect imaging. The relatively high effort in technical equipment combined with an experienced team will be justified by the good results of this endoneurosurgery.