Topology optimization has been successfully used for improving vibration damping in constrained layer damping structures with viscoelastic materials. Reinforcing carbon nanotubes in a polymer matrix greatly influences the mechanical properties of the polymer. Such nanotube-reinforced polymers (NRP) can be used to further enhance the damping properties of the constrained layer structures. The inclusion of nanotubes into a polymer matrix provides a new design variable in the topology optimization studies on such structures. In this work, the topology optimization of structures using such NRP as the damping material is performed. The resulting structures show a phenomenal improvement in damping. Moreover, a more efficient method is used for the optimization process. Copyright © 2005 by ASME.