  We calculate the next-to-next-to-leading order correction to the cross
section for top quark pair production in e+e- annihilation in the threshold
region, resumming all O [ (alpha_s/beta)^n (alpha_s^2, beta^2, alpha_s beta) ]
terms of perturbation series. We find that the magnitude of the NNLO correction
is comparable to the size of the NLO corrections.
