The mechanical behavior of Al 6063 metal matrix composites reinforced with agro-waste silica particles was investigated. The composites were prepared by double-stir casting with 2, 4, 6 and 8 vol. % of agro-waste silica particles as reinforcement in the Al 6063 metal matrix. Mechanical properties (hardness, tensile, fracture toughness and impact strength) and density measurements were used to characterize the cast specimens. Test results showed that the silica reinforcement resulted in density reduction and improved mechanical properties compared to the unreinforced Al 6063 metal matrix. However, percentage elongation and fracture toughness reduced gradually with increase in silica volume fraction with the latter above the minimum permissible limit (6-8 vol. %) allowed for aluminum matrix composites. This shows that agro-waste silica particles is a promising reinforcement material for production of low cost aluminum matrix composites.