  In the lecture we review several issues related to recent development in
non-perturbative QCD. The ``instanton liquid model'' reproduces not only the
basic vacuum parameters (the condensates), but even hadronic correlators. New
information obtained from lattice simulations also confirm it. Meanwhile the
model itself was developed into a self-consistent approach, allowing to include
't Hooft interaction to all orders. It was also generalized to non-zero
temperatures and high densities. We discuss one issue, displayed by behavior of
the pion and rho correlation functions: the former has strong non-perturbative
effects at small distances, the latter has none. What happens at $T\sim T_c$
can be answered by dilepton production experiments with heavy ion collisions.
The results definitely indicate large changes in spectral density and "melting"
of the rho meson peak, possibly reaching the rate corresponding to complete
chiral restoration.
