A novel biosensor is developed based on gold nanoparticles modified silicon nanowire arrays. The ordered silicon nanowire arrays firstly have been fabricated via wet etching method. Then, the silicon nanowire arrays are modified by gold nanoparticles, which are directly fabricated into an electrode for detection of bovine serum albumin (BSA) in solution without any pretreatment. The modified silicon nanowire arrays biosensor with the immense surface area and high electrical conductivity shows a good sensitivity and linear range. This facile modification approach could be extended to preparing various Si-based biosensors for other protein characterizations and optical detection of target analyte molecules by surface-enhanced Raman spectroscopy. (C) 2009 Elsevier B.V. All rights reserved.