AbstractPolypropylene/wood flour composites having different nanoclay and glass fiber contents were fabricated by melt compounding and then injection molding. The physical and mechanical properties were evaluated. The results showed that the tensile modulus and tensile strength of the PP/wood flour composites increased with increasing glass fiber content. However, the impact strength of the PP/wood flour composites progressively decreased with increasing glass fiber content. Dimensional stability of the composites could be improved by increasing the glass fiber content. Also, results indicated that the tensile modulus and tensile strength of composites increased with increase of nanoclay up to 4phc and then decreased. However the impact strength and water absorption of the composites decreased with increasing the nanoclay loading. The morphology of the nanocomposites was examined by using X-ray diffraction (XRD). Morphological findings revealed an intercalated form in the sample with 4 per hundred compounds (phc) concentration of nanoclay, which implies the formation of an intercalated morphology and better dispersion than 6phc, and the d-spacing of clay layers were improved in the composite in the presence of compatibilizer. This project has shown that the composites treated with glass fiber and nanoclay will be desirable as building materials due to their improved stability and strength properties.