The controlled polymerization of vinyl chloride (VC) with ter-t-butyllithium (tert-BuLi) was investigated. The polymerization of VC with tert-BuLi at -30 degreesC proceeded to give a high molecular weight polymer in good yield. In the polymerization of VC - 30 to 0 degreesC under nearly bulk, the relationship between the M-n of polymers and polymer yields gave a straight line passed through the origin, but the M-w/M-n of PVC was not narrow. When CH2Cl2 was used as polymerization solvent, the M-n of PVC increased with the polymer yield, and the M-w/M-n of 1.25 was obtained. Structure analysis of the resulting polymers indicates that the main chain structure could be regulated in the polymerization of VC with tert-BuLi. Accordingly, a control of molecular weight of polymer and main chain structure is possible in the polymerization of VC with tert-BuLi. (C) 2003 Elsevier Science Ltd. All rights reserved.