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An approach for shape optimization of three-dimensional solid structures is described. A major consideration in the development of this capability was the desire to use a commercially available finite-element program, such as NASTRAN, for analysis. Since NASTRAN cannot be called a subroutine, a system architecture of independently executable modules was developed, in which sequential execution is controlled by job control language. Also, sensitivities are not commonly available in commercial programs. A material derivative approach was developed to obtain shape sensitivities by postprocessing finite-element boundary stresses stored on files. A parameterized surface description and mesh generation are provided using isoparametric mapping patches. The feasible directions algorithm CONMIN is used for optimization. Several automotive-related examples are used to evaluate the program's effectiveness.