In this study, the effect of silane treatment of Fe3O4 on the magnetic and wear properties of Fe3O4/epoxy nanocomposites was investigated. Fe3O4 nanopowders were prepared by coprecipitation of iron(II) chloride tetrahydrate with iron(III) chloride hexahydrate, and the surfaces of Fe3O4 were modified with 3-aminopropyltriethoxysilane. The magnetic properties of the powders were measured on unmodified and surface-modified Fe3O4/epoxy nanocomposites using SQUID magnetometer. Wear tests were performed on unmodified and surface-modified Fe3O4/epoxy nanocomposites under the same conditions (sliding speed: 0.18 m/s, load: 20 N). The results showed that the saturation magnetization (M-s) of surface-modified Fe3O4/epoxy nanocomposites was approximately 110% greater than that of unmodified Fe3O4/epoxy nanocomposites. This showed that the specific wear rate of surface-modified Fe3O4/epoxy nanocomposites was lower than that of unmodified Fe3O4/epoxy nanocomposites. The decrease in wear rate and the increase in magnetic properties of surface-modified Fe3O4/epoxy nanocomposites occurred due to the improved dispersion of Fe3O4 into the epoxy matrix. (C) 2010 Elsevier B.V. All rights reserved.