X-ray tube with flying focus has a magnet system for deflecting and focusing the electron beam, whereby the magnet system including a carrier that is constructed as an iron yoke and that has four pole projections that are arranged around the axis of the electron beam offset from one another by 90°, on which two pairs of coils (z-coils and &phgr;-coils) are arranged so as to be offset from one another 90°. The individual coils of each pair supplied with a common high-frequency alternating current that deflects the electron beam in the &phgr;-and z-directions, respectively, in a pulsed manner.