The purpose of this study was to describe the technique used to safely identify the petrous carotid artery during expanded endonasal approaches to the skull base. A series of 20 cadaveric studies was undertaken to isolate the vidian artery and nerve and to use them as landmarks to the petrous internal carotid artery (ICA). Twenty-five consecutive paraclival endoscopic cases were also reviewed to determine the consistency of the vidian artery in vivo as an intraoperative landmark to the ICA. These data were then correlated with results from a separate study in which computed tomography scans from 44 patients were evaluated to delineate the course of the vidian canal and its relationship to the petrous ICA. In all 20 cadaveric dissections and all 25 surgical cases, the vidian artery was consistently identified and could be reliably used as a landmark to the ICA. The correlation between anatomical and clinical data in this paper supports the consistent use of the vidian artery as an important landmark to the petrous ICA.