Plasma-induced polymerization (copolymerization) is a new method of polymer synthesis. Different comonomer pairs (methyl methacrylate-styrene, methyl methacrylate-α-methylstyrene, acrylonitrile-α-methylstyrene, methacrylonitrile-styrene, butyl methacrylate-styrene) have been copolymerized by this technique. The results showed that the process proceeds through a living radical mechanism and yields ultrahigh molecular weight macromolecular compounds (pleistomers). So, the reactivity ratio values of the monomers copolymerized by this technique are very close to those yielded by their classical radical copolymerization, and the microstructure of the copolymers is similar to that of their radically obtained homologs. Some characteristics, as well as some solution properties, of the ultrahigh molecular weight copolymers obtained are also presented.