We created novel SERS substrates by metalizing (Ag or Au) Si nanograss fabricated by a Bosch process on single crystalline silicon. We demonstrated that the fabricated SERS substrates are highly sensitive. The sensitivity of the substrates depends on the target molecules, the excitation laser wavelengths and the metal coating on the silicon nanograss. With the optimal excitation condition at 633 nm, an enhancement factor of 6 × 107 can be achieved for trans- 1,2-bis(4-pyridyl)-ethylene (BPE) molecules on the gold coated silicon nanograss substrate.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.