In the present work, a study of the effect of the surfactant nature on the synthesis of polymethylmethacrylate (PMMA) obtained by high frequency ultrasonic radiation and redox initiation is presented. The surfactants used were an anionic: sodium lauryl sulfate (SLS) and a nonionic: nonylphenol etoxilated. Different morphologies, particle size, and microstructures were obtained depending on the surfactant concentration (0.5, 1.0, 1.5, and 2.0)%. The highest conversion values of PMMA were obtained with SLS, resulting in a highly syndiotac tic polymer. High frequency ultrasound is very efficient when ionic surfactants are used. However, for nonionic surfactants ultrasonic irradiation is very inefficient to initiate polymerization, in this case the effect of redox initiation was very marked increasing polymerization conversion. For this, surfactant blends of PMMA/PEO were obtained when redox initiation was used together with high frequency ultrasound. POLYM.