Abstract: The invention relates to a method for continuously mixing fibers with a binding agent for producing fiberboards in a continuously operating mixing apparatus which comprises at least one mixing chamber and one or a plurality of mixing tools fastened to a rotating mixer shaft, wherein the mixing tools mix the fibers with the binding agent and convey it in a conveying direction through the mixer. Said method is characterized in that the rotational speed (n) of the mixer shaft and the diameter (d) of the mixing chamber are matched to each other with the proviso that the (nominal) centrifugal acceleration of the fibers in the region of the mixer inside wall is 10000 to 30000 m/sec2.