Abstract: A mixing nozzle for injection molding of plastic materials. The invention includes a casing which has a bore therein for receiving a cylindrical mixing element. Each end of the mixing element has a bore therein which terminates at a center section. The bores communicate through holes which radially extend from grooves in the end sections to the bores. The grooves communicate with a center section which is characterized by a plurality of ribs circumferentially passing thereabout. The areas between the ribs are of reduced diameter, while the ribs themselves are of a diameter equal to the major portion of the mixing element. Longitudinal grooves interconnect the areas between the adjacent ribs. Liquid plastic carrying a pigment is introduced into one end of the casing, passes through the bores and holes, along the grooves, and then circuitously finds its way through the center section to the opposite end where the plastic passes along the grooves, down the radial holes, into the bore, and into an injection mold.