A device for providing assistance in otologic surgery of a patient who is to be implanted with a cochlea implant. The device includes a mechanism for identifying the positions of an entry point (21) on the surface of the cochlea and of a control point (20) in the sinus tympani, and operable via the external auditory canal; a processor (100) to respond to the coordinates of the points to determine a straight-line path (T) passing through the two points and defining a docking point (22) on the outside surface of the mastoid bone; and a drilling mechanism (25, 27) for drilling a passage up to the cochlea through the mastoid bone along the straight-line path, so as to create a passage up to the cochlea.