The vibrational normal modes of the free base porphine (FBP) have been investigated within the framework of the density functional theory (DFT). The scaling of the internal force constants has been performed using a least-squares method, and a general valence force field was deduced for the free base porphine with D-2h symmetry. To check the vibrational assignments for the normal modes having the A(g) symmetry, the resonance Raman intensities have been predicted. It is shown that the A term part of the scattering tensor is able to explain most of the observed resonance Raman enhancements for the electronic transitions lying in the Q band.