A systematic study of low mass dilepton production from π-ρ interactions in a hot medium is presented. Applying finite temperature perturbation theory the dilepton rate, respectively the virtual photon rate, is computed up to order g_ρ^2. For dilepton masses below the ρ the two-body reactions ππ→ργ^*, πρ→πγ^*, and the decay process ρ→ππγ^* give significant contributions. Non-equilibrium contributions to the thermal rate are estimated, including the modification of the particle distribution

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... ion with non-zero pion chemical potential. The comparison of the dilepton rate with the recent data measured in nucleus-nucleus collisions at SPS energy by the CERES Collaboration is also performed. It is shown that the additional thermal dileptons from π-ρ interactions can partially account for the access of the soft dilepton yield seen experimentally.