This article deals with the measurement and evaluation of the circularity of the machine DMG MORI -DMU 50 using the measuring system Ballbar QC20-W, which can measure the circularity of the machine using circular interpolation. Furthermore, the system can evaluate machine errors or measurement errors. This can prevent a number of problems, such as financial losses, compliance with the required accuracy and adherence to order deadlines. All three planes of the machine tool were measured -XY, YZ and ZX. In each plane, accuracy (roundness deviations) was measured at three values of feed rate 1000, 1500 and 2000 m.min-1. Each measurement was evaluated and in the end the dependence in individual planes on the feed rate is given.