The tensile properties of polypropylene (PP) filled with hollow glass beads have been measured at room temperature to identify the effects of the particle contents, size and its distribution on them in the present article. The mean diameters of the fillers were 11, 35, and 70 pm, and they were named as TK10, TK35, and TK70 respectively. The surface of these particles was pretreated with silane coupling agent. The results showed that the yield stress (sigma(y)) decreased gently for PP/TK70 systems, whereas decreased relatively obviously for PP/TK35 systems with increasing the volume fraction (phi(f)) of the fillers. When phi(f) was less than 5%, the tensile strength at break (sigma(b)) of the composites increased with the increase of phi(f). When phi(f) was more than 5%, sigma(b) was almost a constant for PP/TK70 systems, while sigma(b) decreased linearly for PP/TK35 systems. The tensile fracture strain (4) of the composites decreased suddenly when phi(f) was less than 5%, and then decreased slightly with increasing phi(f). When phi(f) was 10%, sigma(y) and sigma(b) increased while epsilon(b) decreased with the increase of the bead diameter. Furthermore, the (T. was predicted by means an equation proposed in the previous work, and good interfacial adhesion was shown between the hollow glass beads and the matrix. (c) 2007 Wiley Periodicals, Inc.