Al-Zn-Mg alloys reinforced with different volume fractions of SiC particulates were prepared by a liquid-metallurgy technique. The mechanical properties in uniaxial tension and compression were evaluated, and fractographic observations were made on the fracture surfaces. The distribution of SiC was quite uniform in the extruded condition, and the mechanical-property data show that the composite properties were inferior to those of the control alloy; they essentially showed a decreasing trend with increasing volume fractions. These observations can be explained in terms of the particle distribution, the porosity and the interfacial characteristics.