An erosion resistant aerodynamic fairing for a rotor blade. A fairing body is formed from at least one reinforcing fiber layer set in a cured resin. An erosion resistant pre-form is fixed to an outer surface of the fairing body. The erosion resistant pre-form comprises a thermoplastic film outer layer fused to a fiber substrate. The fiber substrate of the erosion resistant pre-form is impregnated with the cured resin of the fairing body which fixes at the preform to the fairing body.