The magnetic field generated by the magnetization has been calculated for films with arbitrarily rough surfaces for the case in which the magnetization is uniform throughout the film. Simple results are obtained on the assumption that the film surface is not too ``ragged,'' i.e., for the case in which the inclination of the local film surface relative to the mean surface is fairly small (<45°). A rough estimate of the demagnetizing factor for a direction in the plane of the film is given by&pgr;⟨p2⟩/&lgr;d, where⟨p2⟩is the mean square deviation of actual film surface from the mean surface, &lgr; the predominant wavelength of the surface roughness, anddthe film thickness. The results are discussed in the context of induced uniaxial anisotropy and ferromagnetic resonance.