A previous study demonstrated that the impact strength of poly(methyl methacrylate) resin can be improved by including randomly distributed 6-mm lengths of ultra-high-modulus polyethylene (UHMPE) fibre. In this study the effect of varying the fibre length on impact strength, fibre distribution and manipulative properties of the resin were investigated. A scanning electron microscopic examination of fibres at the fracture surface was also carried out. It was found that a 1 % by weight loading of 3-mm, 6-mm and 12-mm fibre significantly improved impact strength when compared to control resin, the 3-mm and 6-mm groups performing significantly better than the 12-mm group. The 3-mm and 6-mm fibres afforded the optimum manipulative properties in the mixing and processing of the resin. Scanning electron microscopy revealed evidence of fibre pull-out.