The validity of transition state theory is examined for the bimolecular reaction of Li+HF-->LiF+H. Accurate three-dimensional quantum scattering theory calculations of the cumulative reaction probability are reported for energies ranging from threshold (0.255 eV) up to 0.600 eV and a total angular momentum J of 0. Transition state theory estimates of the effect of both the entrance and exit channels on the cumulative reaction probability are reported for the same energy range and J value. The transition state theory results are found to provide an accurate description of the smoothed energy dependence of the cumulative reaction probabilities with a maximum disagreement between the two calculations of about 25% arising at the highest energy considered of 0.6 eV