Cast structures offer significant potential for weight reduction by applying numerical optimization methods. However, optimization techniques have been rarely used by industry in these applications because of either the large computational resources required or the extensive time required to set up the optimizations. Improvements in topological optimization and faster computers have overcome some of these problems.This paper shows some examples of recent optimization studies as applied to cast structures. Topological optimization studies are performed using ANSYS finite element software. Sizing optimization studies were performed with MSC/NASTRAN software.These studies have shown that optimization can be effectively applied to solid structures, assuming that the critical loads can be modeled with linear analyses.