Silver nanocaps were prepared by chemical synthesis combined with physical evaporation technique, and characterized using TEM, SEM and UV-vis-NIR spectroscopy. The surface-enhanced Raman scattering (SERS) activities of these nanoparticles were investigated using methylene blue (MB) as probe molecule. The enhancement factor was estimated to be as large as 4.2 x 10(7). The results demonstrate that these silver nanocaps are promising for SERS applications in detection and analysis of molecules. (C) 2007 Elsevier B.V. All rights reserved.