The cranial anatomy of Megalohyrax eoceanus Andrews, 1903, a pliohyracid (Hyracoidea, Mammalia) from Oligocene levels of the Jebel Qatrani Formation of the Fayum Depression in Egypt, is described. Megalohyrax is the largest of the Fayum hyracoids, its skull is 391 mm long and the specimen described here is probably the best-preserved pliohyacid skull known. Megalohyrax has a strong lambdoid crest, a primitive alisphenoid canal, a notch for the minor palatine neurovascular group, orbits which are not anteriorly displaced, and a broad contact between the maxilla and frontal. In all of these features, Megalohyrax differs from modern hyracoids. Contrary to previous suggestions, the dental formula of Megalohyrax is 3.1.4.3, not similar to early sirenians (which have 5 premolars). Basioccipital morphology suggests that Megalohyrax may have had a eustachian sac.