Electrospun Nylon 6 nanofibers, in the form of nonwoven fabrics, were impregnated with the dental methacrylate of BIS-GMA/TEGDMA (50150, mass ratio), to prepare the restorative composite resins. Three-point bending test results indicated flexural strength (FS), elastic modulus (E-Y) and work of fracture (WOF) of the nanofiber reinforced composite resins were all significantly increased with relatively small amounts of Nylon 6 nanofibers. The addition of 5% (mass fraction) nanofibers improved FS by 36%, E-Y by 26%, and WOF by 42% over those of the neat resin. SEM observations showed the fracture surface of the composite resin was rough, while the fracture surface of the neat resin was smooth and had large fracture steps. It is suggested that the presence of nanofibers deflected the crack. When the crack finally broke away from the nanofibers, numerous fracture lines and steps were created on the fracture surface, resulting in energy consumption during fracture. (C) 2004 Elsevier Ltd. All rights reserved.