We have used incoherence scatter radar measurements in the polar ionosphere to study the effects of ion composition variations on the E and F region conductivities and conductances. We find that these variations are of minor importance and that during solar minimum conditions the electron density above ~170 km contributes negligibly to the Hall and less than 20% to the Pedersen conductance. This supports similar results obtained by the Chatanika and S¿ndre Str¿mfjord radars but is in contrast to theoretical predictions. ¿ American Geophysical Union 1990