The infrared fundamental intensities of benzene and hexafluorobenzene have been calculated at the MP2/6-311 ++G(3d,3p) level. The theoretical values are in excellent agreement with the averaged experimental C6H6 results having a rms error of 15.3 km mol(-1). However, the theory badly underestimates the CIF stretching and ring deformation intensities Of C6F6 having an overall rms error of 141 km mol(-1). The theoretical results confirm the dipole moment derivative signs previously attributed on the basis of the comparison Of C6H6 and C6D6 derivatives and semiempirical Molecular orbital results. A quantum theory atoms in molecules charge-charge flux-dipole flux interpretation of the theoretical results shows that electronic density changes for out-of-plane vibrations can be explained using a simple bond moment-rehybridization moment model proposed many years ago. However, these changes were found to be much more complicated for the in-plane vibrations involving important charge flux and dipole flux contributions for both molecules as well as contributions from the displacement of equilibrium atomic charges for hexafluorobenzene.