Thin magnetic films (50-100% Ni-Fe) produced by vacuum evaporation at oblique incidence angles (θ) of 30° and 60° were irradiated by 250 kV deuteron dose ( /cm2.s) at temperatures below 50°C. The composition dependence of Ku(uniaxial anisotropy constant) of the films as depodited was almost linear, being positive and large at 50% Ni and slightly negative at 100% Ni. In the case of films of , a slight increase (Ni 80%) or decrease (Ni 80%) in Kufollowed by a slow decrease in was observed with the increase in the irradiation dose. The behavior was almost independent of the direction of the magnetic field applied to the films during the irradiation. In the case of films of , the general behavior of Kuwith the irradiation was the same except that the initial increase or decrease was not clearly observed. These results were considered the result of irradiation enhanced vacancy migration which induced the change of shape and spacing of the "columns" developed in the oblique incidence evaporated films.