We present our most recent results on laser-induced optical reorientation in mixtures made by adding small amounts of organic dyes to nematic liquid crystals. The optical reorientation process is biased by the molecular interaction between dye and nematic host, so that the reorientation is dramatically enhanced. Measurements of this enhancement have been performed on several guest-host mixtures in order to get information on the nematic-dye molecular interaction. Our results seem to indicate that the presence of strong dipolar group as CN in the nematic host may play a significant role in the observed effect.