Abstract: A materials mixer, suitable for mixing concrete, comprises a generally cylindrical housing (10) which houses a mixing chamber (15) consisting of an upper, dry mixing chamber portion (2), a central, wet mixing chamber portion (3) and a lower, discharge chamber portion (4). The materials mixer has an entrance (20) for materials to be mixed and an exit (25) for the complete mixture, between which are a plurality of rotating members (30, 40, 50, 60) which disrupt the flow of materials through the chamber (15) causing mixing of the materials. The shape of the mixing chamber is defined by a plurality of baffle plates (11, 12, 16) which help determine the path of the materials though the chamber.