Next-to-leading-order temperature corrections to correlators in QCD

Corrections of order T^4 to vector and axial current correlators in QCD at a finite temperature T<T_c are obtained using dispersion relations for the amplitudes of deep inelastic scattering on pions. Their relation with the operator product expansion is presented. An interpretation of the results in terms of T-dependent meson masses is given: masses of \rho and a_1 start to move with temperature in order T^4.