Instanton density at finite temperatures

For low T new strict results for the instanton density n(T) are reported. Using the PCAC methods, we express n(T) in terms of vacuum average values of certain operators, times their calculated T dependence. At high T, we discuss the applicability limits of the perturbative results. We further speculate about the possible behavior of n(T) at T∼${\mathit{T}}_{\mathit{c}}$.