We present a derivation of covariant kinetic equations for nucleons and deltas within a model of quantum hadrodynamics, which includes scalar, vector and pseudo-scalar mesons. By generalizing the Kadanoff-Baym equations to relativistic fields and using the gradient expansion as well as the quasi-particle approximation for the baryons, we find kinetic equations with covariant collision integrals of the Uehling-Uhlenbeck type. These relativistic LandauVlasov equations for nucleons and deltas are solved numerically for two counter-streaming nuclear-matter currents. Using the microscopic expressions we find — due to modifications of the baryon properties in nuclear matter — strong medium effects on relaxation processes in intermediate-energy heavy-ion collisions.