Trans-4.4' -bis(alkyl) difluorostilbenes were reported to be superior LC compounds with low viscosity and high △n except for having low UV-stability. We have attempted to introduce of fluorine to the benzene ring or to substitute one of the two benzene rings for cyclohexane ring for obtaining LC compounds with higher UV-stability. It was found that the former compounds were characterized by lower viscosity and the latter compounds showed large K33/K11 values. The mixtures for STN-LCDs with fast response time were developed using these new materials.