Methylene Blue or Toluidine Blue O were covalently bound to an activated silicone polymer by means of an amide condensation reaction. UV-visible absorption spectra confirmed that the dye was surface bound. The new polymers with covalently attached dye display significant bactericidal activity against Escherichia coli and Staphylococcus epidermidis with a 99.999% reduction in viable bacteria after four minutes exposure to a low power laser.