© 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.The effects of sensitivities on the performance of aerodynamic design optimization were evaluated. Sensitivities were obtained by both analytical and finite-difference approaches. A sensitivity code was developed to analytically obtain sensitivities for the two-dimensional Euler equations using the material derivative concept of continuum mechanics. Several inverse design optimizations were performed to evaluate the merits of the analytical approach in comparison with the finite-difference approach. The results show that the analytical approach provides accurate sensitivities consistently, improves the convergence of design cycle, and hence reduces the design cost.