According to the hypothesis of Jannetta, an arterial compression of the left root entry zone (REZ) of cranial nerves IX and X by looping arteries could play an important role in the pathogenesis of essential hypertension. In an initial anatomical study, the positions of the left vagus and glossopharyngeal nerves in the skull were radiographically determined in 10 cadavers. By using a pattern of REZ topography developed from this information, the angiographic findings in 107 hypertensive and 100 normotensive patients were then compared retrospectively. In 80% of the angiograms of the hypertensive patients that could be evaluated, an artery crossed the left REZ of cranial nerves IX and X. Most frequently, this was the posterior inferior cerebellar artery (35.3% of cases), followed by the vertebral artery (29.4% of cases) and the anterior inferior artery (19.1% of cases). In 9 cases (13%), both the posterior inferior cerebellar artery and the vertebral artery appeared in the REZ. Frequently, a larger diameter of the left vertebral artery was found. The angiograms of normotensive patients that could be evaluated revealed an artery in the REZ in only 34.5% of cases. Our results support the hypothesis that essential hypertension may be associated with neurovascular compression of the left REZ of cranial nerves IX and X.