Abstract: A drilling apparatus for the preparation of bone cavities includes a plurality of drills which are simultaneously driven in opposite direction with the cutting surfaces of each drill overlapping the cutting surfaces of at least one other drill to provide intersecting bone cavities. The drills may be driven by gearing located within the drill head or by gearing located in an attachment suitable for connection to a conventional drill head having a single output drive. The drills may be disposed along a straight or curved line or may be disposed in a triangular relationship with the axis of rotation of one of the drills being transversely movable relative to the axis of rotation of another drill.