Dispersion relation for the whistler mode waves in an anisotropic warm magnetoplasma in the presence of a parallel electric field has been derived. The modifications in the whistler mode instability produced by cold plasma injection to an infinite uniform anisotropic plasma (A<1) in the presence of a parallel electric field have been studied. This study has been performed with the plasma parameters similar to those observed in the equatorial magnetosphere at 6.6 RE. The electric field is found to have pronounced effect for small values of nc/nw and extends the range of instability in k space toward higher wavelengths. The cold plasma injection increases the range of instability in k space toward lower wave lengths. The effects of electric field seem to be insignificant for large values of nc/Nw.