In this study, the cooling performance and mass of a pin-fin radial heat sink were optimized. A radial heat sink with pin fins was examined numerically to obtain a lighter heat sink while maintaining a similar cooling performance to that of a plate-fin heat sink investigated in a previous study. Both natural convection and radiation heat transfer were considered. Experiments were performed to validate the numerical model. The average temperature and mass of the heat sink for various types of fin arrays were compared to determine an appropriate reference configuration. The effects of various geometric parameters on the thermal resistance and mass of the heat sink were investigated; these indicated that the system was sensitive to the number of fin arrays, as well as the length of the long and middle fins. Multidisciplinary optimization was carried out using the three design variables to minimize the thermal resistance and mass simultaneously, and Pareto fronts were obtained with various weighting factors. A design for the optimum radial heat sink is proposed, which reduces the mass by more than 30% while maintaining a similar cooling performance to that of a plate-fin heat sink. (C) 2011 Elsevier Ltd. All rights reserved.