Poly(undecylbithiophene), formally an alternating copolymer of thiophene and 3-undecylthiophene, has been synthesized via two different protocols. Direct oxidative polymerization of 3-undecyl-2,2'-bithiophene with ferric chloride in nitrobenzene (P3UBT-F) and transition-metal-mediated polymerization of 5-bromo-4-undecyl-5'-iodozincio-2,2'-bithiophene (P4UBT-R) have been carried out. Suprisingly, the two materials have been found to possess similar spectral characteristics (vibrational spectroscopy, H-1 NMR) and yet different physical properties. While P4UBT-R has ca. 90% of the head-to-tail motif, the regiochemistry of P3UBT-F could not be established satisfactorily. The former has a higher level of conjugation, but the level of conjugation in P3UBT-F is still comparable to that reported in the literature for regioregular poly(3-alkylthiophene)s (P3AT). Preliminary conductivity measurements show that the usually adverse effects of regioirregular structures on conjugation and conductivity can be suppressed substantially by the combination of monosubstitution and "inside" positioning of the pendant group on the bithiophene.