A series of regioregular head-to-tail poly[3-(alkylthio)thiophenes] have been synthesized. The synthetic approach includes the in-situ preparation of 2-bromo-3-(alkylthio)-5-(bromozincio)thiophenes via regiospecific oxidative addition of Rieke zinc (Zn*) to 2,5-dibromo-3-(alkylthio)thiophenes, and the regiospecific polycondensation of 2-bromo-3-(alkylthio)-5-(bromozincio)thiophenes catalyzed by Ni(DPPE)-Cl-2. These poly[3-(alkylthio)thiophenes] are highly regioregular polymers with head-to-tail linkages as high as 90% as determined by proton NMR integration. The structures, solution properties, and solid-state properties of the polymers were also investigated by the analyses of FTIR, UV-vis spectroscopy, and the X-ray diffraction data. The regioregular polymers are soluble in carbon disulfide, however, only slightly soluble in other common organic solvents, such as THF, chloroform, and xylenes. A golden film can be casted from a solution of carbon disulfide. A self-organized lamellar structure of the films was revealed by X-ray diffraction analysis. The p-doped poly[3-(allkylthio)thiophene] films upon exposure to iodine vapor are highly electroconductive with a conductivity range of 10(2) S/cm.