Hollow glass beads (HGBs) are a new kind of filler in rubber, plastics, and coating industries for the production of light, sound, or thermal insulation products with their smooth surface and stiffness. The tensile properties and flexural strength of acrylnitrile-butadiene-styrene copolymer (ABS) filled with HGBs have been measured at room temperature to identify the effects of the particle contents on these properties. The mean diameter of the beads is 70 mu m. The surface of the particles are pretreated with a silane coupling agent. The results show that the Young's modulus increases approximately linearly with the increase in volume fraction (phi(f)) of the HGB. When phi(f) is <5%, the tensile yield stress increases and then decreases with increasing phi(f). When phi(f) is < 15%, the tensile strength at break of the composites increases with the increase of phi(5) and then it remains roughly constant. Similarly, the tensile fracture strain of the composites increases when phi(f) is <5%, and then it decreases with increasing of. Furthermore, the flexural strength increases with an increase of of, and the relationship between them is consistent in a quadratic equation. The improvement of the tensile and flexural properties of the composite may be attributed to the smooth spherical surface and good interfacial bonding between the ABS matrix and the hollow beads.