Polymerization of (dimethylamino)ethyl methacrylate (DMAEMA) by lanthanocene amide complexes was investigated. The results show that (MeC5H4)(2)LnN(i-Pr)(2)[tetrahydrofuran (THF)] (Ln = Y, Er, Yb), (MeC5H4)(2)YbNC5H10(HNC5H10) (HNC5H10 = piperidine), (MeC5H4)(2)YbNPh2(THF), and (t-BuC5H4)(2)YbNPh2(THF) are effective initiators for the polymerization of DMAEMA, and the molecular weights of the polymers obtained exceed 100 x 10(3). The polymerization reactions can be varied over quite a broad range of temperatures from -78 to 40 degreesC. The central metals and amido groups had a significant effect on the polymerization activity. The increasing activity of central metals and amido groups was Yb < Er < Y and NPh2 < N(i-Pr)(2) < NC5H10, respectively.