A new type of composite was designed and tested which has greater fracture toughness under impact loading conditions than conventional fibre-reinforced composites. This composite is strain-rate sensitive and can be more than twice as tough as conventional composites having the same matrix and fibre. The key concept used was to coat the reinforcing fibres with a thin layer of viscous fluid in order to maximize the shear stress acting on the fibres during the fibre pull-out. At a given strain-rate the shear stress can be optimized by changing the fluid viscosity and thickness of the coating. The optimum results are obtained when the frictional force is equal to the fibre strength.