  This talk reviews the status of QCD calculations of photon and dilepton
production rates in a Quark-Gluon plasma. Theses rates are known to order
${\cal O}(\alpha_s)$. Their calculations involve various resummations to
account for well identified physical effects that are briefly described.
Lattice calculations of the spectral functions give also access to the dilepton
rates. Comparison with perturbative results points to inconsistencies in both
approaches when the dilepton energy becomes small.
