In this paper, γ-aminopropyltrimethoxysilane treated poly(vinyl chloride) (PVC)/rice husk ash (RHA) composites were successfully prepared by a reactive extrusion process. Experimental results revealed that both the tensile modulus and tensile strength increased at all silane coupling agent concentrations. The composites with 1 wt% silane exhibited the highest impact strength with 44 % increment. For the untreated composites, poor interfacial adhesion between PVC and RHA was clearly observed. Below the glass transition temperature (Tg), the silane induced higher storage modulus (E ′) but it seemed to be independent of E′ above Tg. Total water absorption at 90 days reduced by 38 % when the silane was added at 1 wt%, which confirmed that some voids were eliminated.