Anionic polymerization of 2-(t-butyldimethylsiloxyethyl) methacrylate (ProHEMA) was performed with potassium ethanolate as an initiator in tetrahydrofuran. It was found that the potassium ethanolate-initiated polymerization of ProHEMA proceeds smoothly at ambient temperature to 90% monomer conversion. The polymerization was initiated by the addition of ethanolate at the double bond in ProHEMA. It is considered that complexation of potassium cation with the ProHEMA molecule increased the nucleophilicity of the oxonium anion to increase the initiation ability. Based on the C-13 n.m.r. analysis, poly(ProHEMA) obtained with potassium ethanolate was syndiotactic rich in microstructure. This is also explained by the bulky counter cation complexed with monomer molecules, which controls monomer insertion around the growing centre. This polymerization method can be applied to a synthesis of an end-functionalized poly(2-hydroxyethyl methacrylate) (poly(HEMA)).