Abstractp‐Trimethylsilylstyrene was found to be polymerisable anionically. When the reaction is carried out at low temperature in THF as solvent the polymer—poly(p‐trimethylsilylstyrene)—is obtained in a quantitative yield and exhibits a low polydispersity. The glass transition temperature, viscosity‐molecular weight relationships, and1H and13C NMR spectra were investigated in order to compare the influence of the trimethylsilyl group located at the benzene nucleus with respect to polystyrene and some otherp‐subtituted polystyrenes. The presence of the trimethylsilyl group in para position of the aromatic nucleus results in an increase of the rigidity of the polymer chain and in an increase of the glass transition