Epoxy resins are inherently brittle. Thus they are toughened with reactive liquid rubbers or core-shell elastomers. Surface-modified silica nanoparticles, 20 nm in diameter and with a very narrow particle size distribution, are available as concentrates in epoxy resins in industrial quantities since 10 years. Some of the drawbacks of toughening, like lower modulus or a loss in strength can be overcompensated when using nanosilica together with these tougheners. Apparently there exists a synergy as toughness and fatigue performance are increased significantly. In this article the literature published in the last decade is studied with a focus on mechanical properties. Results are compared and the mechanisms responsible for the property improvements are discussed. (C) 2013 Elsevier Ltd. All rights reserved.