Eight operations were done on four formalinfixed cadavers to assess the technical feasibility of an approach which provide remove more than half of the clivus via extradural drilling out of the petrous apex. This approach also provides exposure of the mid and lower parts of the basilar artery, its branches, vertebrobasilar junction, the sixth nerve, and anterior face of pons and medulla without the need for division of the tentorium, manipulating or removing the inner ear organs and vestibulocochlear nerve.