A liquid-crystal display device of the twisted nematic type which comprises (1) a pair of electrode substrates facing each other, each being provided with an orientation membrane, the surface of which is treated by rubbing, and (2) a specific nematic liquid-crystal composition having a positive dielectric anisotropy containing a pyrimidine derivative of formula (I), ##STR1## wherein R.sub.1 and R.sub.2 are each a straight-chain alkyl group of 1 to 12 carbon atoms and containing an optically active substance, sandwiched between the two electrode substrates and arranged so that the axes of the liquid-crystal molecules will be twisted by an angle .phi. in the range of 210.degree..ltoreq..phi..ltoreq.300.degree., which shows excellent multiplex driving characteristics and suitable for use in display units of heavy-duty multiplex driving type.