A large-scale lambda-DNA network on a mica surface was successfully fabricated with a simple method. Silver nanoparticles capped with the cationic surfactant cetyltrimethylammonium bromide (CTAB) were self-assembled onto a two-dimensional DNA network template by electrostatic interaction and formed nanoporous silver films, which can be used as active surface-enhanced raman scattering (SERS) substrates. Two probe molecules, Rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP), were studied on these substrates with very low concentrations, and great enhancement factors for R6G (0.21 x 10(10)-4.09 x 10(11)) and 4-ATP (approximately 1.70 x 10(5)) were observed. It was found that the enhancement ability was affected by the DNA concentration and the electrostatic absorption time of the CTAB-stabilized silver nanoparticles on the DNA strands. These SERS substrates formed by the self-assembly of silver nanoparticles on DNA network also show good stability and reproducibility in our experiments.