The simultaneous compounding of polypropylene with several mineral fillers was investigated. The mineral fillers were selected on the basis of their size and shape which was spherical (glass beads), sheet-like (mica) or fibrous (wollastonite). In addition, one filler with a considerably smaller particle size (fly ash) was selected. The results of single components were as expected. In multicomponent compounding, the best mechanical properties were attained by the simultaneous use of two or more fillers. This was true for all mechanical properties. In the light of the results, it is evident that the need for a matrix polymer and other fillers can be reduced by the use of a filler with a small particle size without impairing the mechanical properties of the composite. It seems that multicomponent compounding yields somewhat better properties than single-component mineral compounding of thermoplastics. In practice, multicomponent compounding is possible using the same process as for single-component compounding.