Abstract: The invention relates to a Resin Transfer Moulding (RTM) process for manufacturing fiber-reinforced components (31) with at least one closed or undercut space (35). A two-part mould with a cavity is charged with reinforcing fibers and a shape-stable supporting core of wax that can be melted out of the cavity. The core is produced from a cast preform by means of at least one shape-forming step. A plastic matrix capable of flowing is injected into the cavity of the closed mould forming a shaped fiber-composite mass and hardened to give the fiber-reinforced component (31). The shape-stable fiber-reinforced component (31) is removed from the mould and subjected to tempering. During tempering the core is melted and drained off from the fiber-reinforced component—leaving behind a closed or undercut space (35)—and the molten core material is cast to provide a new preform (1).