Polyester resin exhibiting optical anisotropy in molten state and composition thereof

A polyester resin comprises 35 to 90 mole percent of the unit (I), 0.5 to 20 mole percent of the unit (II), 0.5 to 45 mole percent of the unit (III) and 0.5 to 45 mole percent of the unit (IV), exhibiting the anisotropy in its molten state. It may further comprise 0.5 to 45 mole percent of the unit (V). The composition is here presented, comprising the polyester resin as defined above and up to 95 percent by weight of an inorganic filler.