While studying dark matter scattering processes in the early Universe, usually, finite temperature effects are included through a thermal averaging of the zero temperature (vacuum) matrix elements,and through corrections to particle masses and phase-space densities in a thermal bath. In this talk, I shall discuss the additional finite temperature NLO corrections to the scattering matrix elements. In particular, approximate analytical forms of these corrections will be derived, which can then be conveniently incorporated in the Boltzmann integro-differential equations for the dark matter distribution function. I shall consider as an example scalar thermal loops to illustrate certain features of these corrections.