Abstract: The invention is directed to an indexing attachment for a numerically controlled milling machine, comprising an indexing spindle rotatably supported in the casing for receiving a workpiece chuck, a bottom plate for fixing the casing on a worktable, and clamping means for fixing the indexing spindle in the various indexing positions. The indexing attachment is to be of simple and inexpensive structure and intended to permit--without any drive means of its own--programme-controlled indexing operations and thus milling steps along five axes. To this end the indexing spindle (10) of the indexing attachment (8) is adapted to be coupled with a driver (4) mounted on a part (2) of the milling machine and to be driven by programme-controlled motions of the milling machine.