Machine beds and frames are predominantly manufactured from grey cast iron and in the form of welded steel structures. On account of their technical and economic advantages, cast minerals or epoxy resin-bound polymer concretes have additionally established themselves since the 1980s. Ultra-High Performance Concrete (UHPC) has been used successfully in machine tools for about 5 years now. This article describes the machine manufacturer's requirements for concrete, above all with regard to precision, dimensional accuracy and freedom from cracks. It matches these challenges against the knowledge of the civil engineers and shows how the problems can be technically solved. Numerous application examples demonstrate the successful use of UHPC in mechanical engineering.