Abstract: A tool for slitting a casing of a cable. A knife blade is held between a pair of holder halves. Slots in the holder halves along a part line form an opening between the holder halves of a size to receive the cable for movement axially through the opening. A corner portion of the knife blade extends from an edge of the opening transversely of the opening a sufficient distance to slit the casing of the cable without penetrating conductors of the cable as the cable is advanced along the opening.