The synthesis of oriented polyacetylene films was investigated by using a nematic liquid crystal as a polymerization solvent. As a result, when polymerization was carried out on a quiesent surface of the nematic catalyst solution, partially oriented polyacetylene films were obtained. On the other hand, in the polymerization under a flow of the nematic catalyst solution, highly oriented films were obtained. The order parameter of the oriented sample, estimated from polarized absorption spectra, was about 0. 57. The maximum value of parallel electrical conductivity of the films doped with iodine was 4600 S/cm, while that of the films doped with arsenic pentafluoride was 11000 S/cm.