  We present a systematic study of the vector--axial-vector mixing (V-A mixing)
in the current correlation functions and its evolution with temperature within
an effective field theory. The $a_1$-$\rho$-$\pi$ coupling vanishes at the
critical temperature $T_c$ and thus the V-A mixing also vanishes. A remarkable
observation is that even for finite $m_\pi$ the $\rho$ and $a_1$ meson masses
are almost degenerate at $T_c$. The vanishing V-A mixing at $T_c$ stays
approximately intact.
