In the attempts to derive from theory the magnetization curve, in the region of rotational magnetization, for well annealed ferromagnetic polycrystals, a generally recognized complication is the possible existence of internal fields caused by the out of alignment of the magnetization vectors of the grains. However, if such internal fields do not really exist, a simple deduction by the usual formal treatment predicts that the magnetization curves of polycrystals, of the same crystalline structure and having the same sign for the values of the principal anisotropy constant, can be brought into coincidence by expressing the intensity of magnetization and the field in proper reduced units'. This prediction is checked experimentally by measurements on iron and an iron alloy containing 15 percent cobalt by weight. In each case, it is found that the normal magnetization curves for various temperatures can be brought into coincidence in the manner as indicated. It is therefore concluded that the effect of internal fields on the process of magnetization in the case of polycrystals cannot be any greater than that in the case of single crystals. The absence of wide spread internal fields of magnetic origin in polycrystals during rotational magnetization is then discussed in the light of recent developments in the domain theory.