The ponderomotive acceleration of multispecies ions due to circularly polarized electromagnetic waves propagating parallel to the magnetic field is calculated. When applied to a low frequency left-hand circularly polarized wave, the results show differential accelerations among the different ion species. We demonstrate that differential acceleration of ion species by the ponderomotive force can occur even in the absence of a parallel electric field component. Our work extends the results previously obtained by Li and Temerin (1993) who considered the ponderomotive acceleration due to obliquely propagating Alfv¿n waves. ¿1996 American Geophysical Union.