Studies have been conducted on the use of the directional properties of composite material to provide design improvements for fighter aircraft. The TSO (Aeroelastic Tailoring and Structural Optimization) computer program, developed by the Air Force Flight Dynamics Laboratory, was used in these investigations. The configurations evaluated covered a wide spectrum of fighter aircraft aerodynamic surfaces, including the F-15 composite wing, a preliminary design horizontal tail, a prototype aircraft wing, and a future conceptual aircraft wing. Both drag reduction and increased roll effectiveness, with no weight cost, are predicted for the F-15 composite wing. A unique minimum weight design is shown for the preliminary design horizontal tail, in which the anisotropic characteristics of the composite material are used to perform the dual function of strength and flutter balance weight. A more conventional optimum flutter solution, based upon outer panel wing root pitch restraint increases, is shown for the prototype aircraft wing. Finally, significant wing twist, offering potential aerodynamic benefits, can be obtained on the conceptual aircraft wing.