Polythiirane containing pendant mesogenic stilbene units was synthesized by ring opening polymerization of the corresponding monomer. The synthetic convergent pathway used for the monomer synthesis involved several steps including a Wittig reaction in order to obtain the stilbene unit. The insoluble polymer was characterized by high resolution CP/MAS 13C NMR. The thermotropic liquid crystalline mesomorphism of the polymer was studied by conventional methods. A mechanical dynamical thermal analysis completes the polymer characterization.