  We study the possibility of $\rho-a_0$ mixing via N-N excitations in dense
nuclear matter. This mixing is found to induce a peak in the dilepton spectra
at an invariant mass equal to that of the $a_0$. We calculate the cross section
for dilepton production through mixing and we compare its size with that of
$\pi-\pi$ annihilation. In-medium masses and mixing angles are also calculated.
Some preliminary results of the mixing effect on the dilepton production rates
at finite temperature are also presented.
