Abstract: A method for compensating the effects of misalignment between deflecting magnetic fields and a linear accelerator in a race track microtron where properly injected and accelerated electrons travel along successive complete orbits numbered in sequence comprising the steps of generating on both sides of the linear accelerator a compensating magnetic field perpendicular to the common plane of the orbits, each field intersecting all complete successive orbits and having a field strength in the regions of the intersections varying stepwise from intersection to intersection, and simultaneously varying the field strength at the intersections while maintaining a linear relationship between the field strength at an intersection and the number of the intersecting complete orbit.