Solvent effect on the ZFS constants, D and E, induced by electron spin-spin coupling (SSC) in the low-lying triplet states of the aza-aromatic molecules pyrazine and quinoline, were calculated using multiconfigurational self-consistent field wave functions and the polarized continuum model (PCM0). The second-order spin-orbit coupling (SOC) contribution to the splitting of the 3nπ* state of pyrazine accounts for about 30% of the total D value, while for the splitting of the 3ππ* state of quinoline it was found to be almost negligible.