The objective of this study was to perform a 3D aerodynamic shape optimization on a ducted fan propulsion system configured for cruise flight on an aircraft. The initial shapes of the duct and hub were determined using a basic grid searching optimization approach. An efficient optimization algorithm was created that utilized the BFGS searching technique with a QuasiNewton line search to refine the initial geometry. The ducted fan was chosen to be controlled by 13 control points connected using a combination of splines, ellipses and conics. The optimum design resulted in a 33.54% and 36.45% reduction in drag for the duct and hub respectively. The propeller thrust was also increased by 141.49%. The optimization methodology used throughout this study proved to be an efficient technique in finding the optimal design to within a high degree of resolution based on the entire design space considered.