In order to study the magnetism of rare-earth (RE) intermetallics, we must consider simultaneously the crystal field (CF) and magnetic interactions.In the description of the magnetic interaction associated with the RE intermetallic, we must take into account that the 4f electrons of a RE ion are strongly localized and the overlap between 4f orbitals is negligible, so that the direct exchange can be ruled out. In this case the indirect exchange via conduction electrons which is of RKKY type l l / , becomes important and mainly characterizes the magnetic behaviour of RE metals. In the first approximation considering the conduction electrons to be purely itinerants, the coupling between ions i and j will be represented by the isotropic Heisenberg exchange.The CF interaction of these compounds has been treated in the literature taking the ground multiplet of the CF splitting of a R E ion corresponding to a RE intermetallic in an integral way and the CF Hamiltonian has been generally described through Stevens' operators I 2 1 using the Lea-Leask-Wolf notation 131.In this note, we are proposing a model in which we keep only the two lowest levels of the split 4f shell of the R E ion in the study of the CF and magnetic interactions. This approach provides an appropriate theoretical framework for studying the magnetic properties of many R E intermetallics since the highly relevant results of this study are obtained a t low temperatures. The main advantage of the two level models is that they simplify the description of the above-mentioned interactions, providing simple magnetic state equations from which we can obtain the adequate value of the Land6 factor and effective exchange parameter for each RE intermetallic. This may be accomplished putting into these equations the suitable experimental data of the magnetic and crystallographic quantities given in the literature. I ) 24.020 -Niteroi, R J Brazil. ') 20.550 -Rio de Janeiro, R J Brazil. ') 22.723 -Rio de Janeiro, R J Brazil.