We study the possibility of ρ-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 π-π 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.