Heterocyclic group-containing vinyl monomers, 2-(vinylbenzylmercapto) heterocyclic salts, were synthesized and their polymerization and copolymerization with styrene were investigated. Cyclic thioureas incorporating imidazoline, hexahydropyrimidine and benzimidazole nuclei were alkylated by chloromethyl styrene to give quaternary salts that were used as monomers. Homopolymerization of the monomers afforded mainly soluble polymers on high dilution. In the copolymerization with styrene, an alternating nature was suggested from the copolymerization parameters obtained by either the Finemann-Ross method or the Mao-Huglin method. A decrease in alternating copolymerizability was demonstrated.