The microfluidic environment provided by implanted prostheses has a decisive incluence on the viability, proliferatbion and differentiation of cells. In bone tissue engineering, for instance, experiments have confirmed that a certain level of wall shear stress (WSS) is more advantageous to osteoblastic differentiation. This paper proposesa level-set based topology optimization method to regulate fludic WSS distribution for design of cellular biomaterials. The topological boundary of fluid phase is represented by a level-set medel embedded in a higher-dimentioal scalar function WSS is determined by the computational fluid dynamics analysis in the scale of cellular base cells. To achieve a uniform WSS distribution at the solid-fluid interface, the difference between local and target WSS is taken as the design criterion, which determines the speed of the boundary evolution in the level-set model. the examples demonstrate the effectiveness of the presented method and exhibit a considerable potential in the design optimization and fabrication of new prosthetic celllular materials for bioengineering application. Biotechnol Bioeng. 2010; 107; 737-746. (C) 2010 Wiley Periodicals, Inc.