  The behaviour of the broken CP symmetry at finite temperature is examined.
This is achieved through the investigation of the neutron electric dipole
moment $d_n$ induced by $\theta$-term.
  By using thermal QCD sum rules, we find that below the critical temperature,
the ratio $\mid {d_n \over \bar{\theta}}\mid$ slightly decreases but survives
at temperature effects. This evolution implies that CP remains broken at finite
temperature as required by Baryogenesis \cite{Chabab}.
