To overcome some experimental difficulties, a new approach to cyclic polystyrenes with narrow molecular weight distribution is proposed. The well-defined alpha,omega-dibromobutyl polystyrene was prepared by direct coupling of the polystyryl dianion with a large excess of 1,4-dibromobutane. End-to-end ring closure of the alpha,omega-dibromobutyl polystyrene was performed by interfacial condensation between the aqueous phase (hexamethylene diamine) and the organic toluene phase (polystyrene precursor). The limited field of reactions such as at the interface was very effective for ring closure. The conversion of cyclic polymers was very high (more than 80%) at polystyrene precursor concentration of 10(-3) M. The hydrodynamic size of the cyclic polymers was substantially less than that of the corresponding linear precursor.