A series of silver/silicon nanoporous pillar arrays (Ag/Si-NPAs) were prepared by an immersion-plating method through controlling the immersing times and their surface-enhanced Raman scattering (SERS) behaviors to rhodamine 6G (R6G) were contrastively studied. With a concentration of 10(-15) M, the identification of R6G could be performed by all the samples, but the corresponding peak intensities varied largely. This phenomenon was attributed to the size difference of the deposited silver nanoparticles, and the optimal size range for obtaining the strongest SERS signal was determined to be similar to 35-55 nm. Ag/Si-NPA might be an effective substrate for performing highly sensitive SERS detections. (C) 2012 Elsevier B.V. All rights reserved.