The ion motion in the E and F regions relative to the local magnetic field line and the horizontal plane has been determined from the European incoherent scatter (EISCAT) common program 1 version I (CP-1-I) data. The ion motion highly depends on altitude and magnetospheric electric field strength. Under the condition of a strong electric field (|E|>25 mV/m), ions move perpendicularly to the local magnetic field line both in the F region and at the upper part of the E region (≥117 km). This suggests the ions moving by the E¿B drift, which is expected when the ion-neutral collision frequency is much smaller than the ion gyrofrequency. At lower altitudes, however, the ions no longer move perpendicularly to the magnetic field line but move horizontally, as expected from a stronger interaction between the ions and neutrals. Under the condition of a weak electric field (5 mV/m<|E|<10 mV/m) the neutral winds tend to move the ions horizontally everywhere in the E region and even in the F region. The main cause of these ion motions and their dependence on altitude and electric field strength comes from the relative importance of the magnetospheric electric field and the large-scale neutral wind drag to the ionospheric ions. ¿ 1998 American Geophysical Union