  We employ non-perturbative flow equations to compute the equation of state
for two flavor QCD within an effective quark meson model. Our treatment covers
both the chiral perturbation theory domain of validity and the domain of
validity of universality associated with critical phenomena. In the vicinity of
$T_c$ and zero quark mass we obtain a precision estimate of the universal
critical equation of state of the three dimensional O(4) symmetric Heisenberg
model. For realistic quark masses the pion correlation length near $T_c$ turns
out to be smaller than its zero temperature value.
