  We calculate dispersion relations and propagators for the $\sigma$, $\omega$,
$\rho$ and $\delta$ mesons in relativistic nuclear matter with a proton-neutron
asymmetry. In addition to the $\sigma$-$\omega$ and $\delta$-$\rho$ mixings
already present in symmetric matter, mixing occur between all components of the
$\sigma$-$\omega$-$\delta$-$\rho$ system when the proton fraction differs from
1/2.
