A system for monitoring a fiber-reinforced composite component in production or in service. The system includes a composite component having reinforcing fibers which are encompassed by a matrix material; at least one optical fiber arranged to extend in a continuous path over a monitoring area of the composite component for contact with the matrix material; a signal generator configured to transmit an optical signal along the at least one optical fiber; and a detector device configured to detect scattering, and in particular backscattering, of the optical signal transmitted along the at least one optical fiber.