Toluene diisocyanate-based polyurethane iniferters containing tetraphenylethane groups in between polyurethane blocks were prepared by the reaction of isocyanate-terminated prepolymers and 1,1,2,2-tetraphenyl-1,2-ethanediol. When these iniferters were decomposed in the presence of styrene, polyurethane-polystyrene multiblock copolymers were obtained through a "living" radical mechanism. The effect of changing polyol on the T-g, thermal stability, and molecular weight of polyurethane iniferters as well as block copolymers was studied. The molecular weight of the block copolymers increased with increasing both polymerization time and conversion.