Surface plasmons of silver nanorods were investigated by using scanning near-field optical microscopy. Near-field transmission images showed spatially oscillatory patterns in nanorods. The oscillatory features of images are attributable to plasmon-mode wave-functions. From the near-field images and spectra, dispersion relations of surface plasmon modes for various silver nanorods are obtained. It is found that dispersion relation of a nanorod is dependent on its diameter. The spectral features obtained are compared with those for gold nanorods. (c) 2005 Elsevier B.V. All rights reserved.