A method of making rotary driven brushes, particularly road-sweeping brushes, by arranging bunches of bristles (2) so that their one ends (2a) extend into a mould (3) for forming the brush base (1), and applying into the mould (3) around the ends (2a) of the bristles a quick-setting liquid plastics material, generally a micro-cellular elastomeric polymer material such as polyurethane foamed by adding water thereto, and allowing the plastics material to set to secure the brush base to the bristles.