Copolymerization of acrylamide (AAm) with styrene (St) was carried out in the presence of methyl ethyl ketone (MEK), methyl isopropyl ketone (MIK) and t-butyl methyl ketone (tBMK) without any conventional initiator in tetrahydrofuran (THF) at 60¡C. The copolymerization of AAm with St proceeded readily in the presence of the MEK, MIK, and tBMK, while no copolymerization of AAm with St proceeded in the absence of these ketones under the same conditions and no homo-polymerization of St proceeded even in the presence of the ketones. The reactivity ratio of monomer AAm (r 1 ) is smaller than that of St (r 2 ) in all of the copolymerization systems, and increases as the order: MEK < MIK < tBMK. The conversion of the copolymerizations increases as the same order described above. The interaction