A cathode ray tube comprises an electron gun with means for generating electron beams. External magnetic fields influence the electron beams and reduce the picture quality. An electrode of the gun includes a part made of a soft-magnetic material, which extends transversely to the electron beams, and two parts, situated to the left and to the right of the electron beams, which extend along said electron beams. Together these parts form a magnetic circuit. Preferably, these parts are strongly magnetically coupled, for example, because they are interconnected or very closely spaced. Interaction of the magnetic circuit formed by said three parts with an external magnetic field causes a Lorentz force on the electron beams. The resultant deviations in the paths of the electron beams largely compensate for the deviations in the paths of the electron beams caused by the effect of the external magnetic field between the electron gun and the display screen.