Polypropylene-vermiculite nanocomposites can be achieved by simple melt mixing of maleic anhydride-modified vermiculite with polypropylene. Maleic anhydride acts either as a compatibilizer for the polymeric matrix or as a swelling agent for the silicate. Compatibilized blends are injection molded directly from polyamide 6 and polypropylene-vermiculite nanocomposites. Scanning electron microscopy observation reveals that a two-phase structure consisting of polypropylene-vermiculite nanocomposite and polyamide 6 is formed in the blends. The absence of vermiculite reflections in the X-ray powder diffraction patterns indicates that the polypropylene-vermiculite phase exhibits nanocomposite characteristics. Tensile test shows that the tensile modulus of the polymer alloy tends to increase with increasing polypropylene-vermiculite nanocomposite content. The tensile strength of composite containing 8 wt % vermiculite is higher than that of pure polyamide 6. Finally, the thermal properties of the nanocomposites are determined by dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric measurements. The effects of maleic anhydride addition on the formation of polypropylene-vermiculite nanocomposite reinforcement and on the mechanical properties of composites are discussed.