The widespread availability of affordable high-performance personal computers and commercial software has prompted the integration of structural analyses with numerical optimization, reducing the need for design iterations by human designers. Despite its acceptance as a design tool, however, structural optimization seems yet to gain mainstream popularity in industry. To remedy this situation, this paper reviews past literatures on structural optimization with emphasis on their relation to mechanical product development, and discusses open research issues that would further enhance the industry acceptance of structural optimization. The past literatures are categorized based on their major research focuses: geometry parameterization, approximation methods, optimization algorithms, and the integration with nonstructural issues. Open problems in each category and anticipated future trends briefly are discussed.