In the course of studies dealing with the synthesis and the characterization of the properties of highly branched polymers with controlled chain parameters, the selectivity of the grafting reaction of polystyryllithium chains onto poly(chloroethyl vinyl ether) has been investigated. To that purpose, a series of isometric poly(chloroethyl vinyl ether) oligomers with precise degree of polymerization, ranging from 3 to 9, were prepared by selective fractionation of a poly(CEVE) of narrow polydispersity into its different n-mers. The latter were used as reactive backbone for grafting PSLi chains. Characterization of the graft copolymers shows that the substitution of chloride off CEVE units is quantitative and yields comblike copolymers with a number of branches corresponding to the number of monomer units in the isometric poly(CEVE) backbone. The poly/CEVE)-g-polystyrenes show the typical solution behavior of star polystyrenes.