Within the next few years, numerical shape optimization based on high fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimization problems, and the adjoint approach - which allows fast and accurate evaluations of the gradients with respect to the design parameters - is seen as a promising strategy. After describing the theory of the viscous discrete adjoint method and its implementation within the unstructured RANS solver TAU, this paper describes application for aerodynamic shape optimization. First wing and fuselage designs of the DLR-F6 wing-body aircraft are presented. A step forward in complexity is considered by applying the adjoint for flap and slat optimal settings of the DLR-F11 model, a wing-body aircraft in high-lift configuration. On all cases presented, optimization were successfully performed within a limited number of flows evaluations.