Living polystyryllithium anions and living polyethyl vinyl ether cations have been successfully coupled. Indeed, no residue of any of the two original homopolymers is observed in the final product, when they are used in a stoichiometric amount. This method has been exploited in order to synthesize AB and ABA polyethyl vinyl ether (PEVE) (A)/polystyrene (PSt) (B) block copolymers with a high efficiency.