We study the consequences of chiral symmetry restoration for thermal production of dileptons in central nucleus-nucleus collisions. We discuss the temperature dependence of various hadronic parameters entering the dilepton cross-section, putting emphasis on universal properties in the vicinity of a 2nd order chiral symmetry restoring phase transition and the constraints on their temperature dependence known from lattice simulations. It is shown that the modifications of the hadron spectrum due to medium effects can lead to important changes of the thermal dilepton production rate in heavy ion collisions. In particular, it can imply the suppression of a thermal [rho] peak.