The problemes of the exact preparation of the hip acetabulum for implantation of total hip prothesis have caused the development of several milling machines. Two sorts of construction predominate. Their disadvantages, especially the fact, that there is now mechanism, while is able to carry of the milled tissue, gave rise to construct a new milling machine. In cooperation with engineers of the branch mechanical engineering a new model was developed. The characteristic features are described and explained by pictures. The milling basket will be fastened on the ground plate by a quick fastener. In this way we get a hemisphere cavity, which is able to absorb all the milled tissue without any residue. A grasp will be connected with the drive shaft and guarantee an exact and rightangeled direction. The clinical tests have shown, that the new milling machine with the grasp especially is qualified for use in the osteoporotic senil bone too.