The structural properties and Raman scattering spectra of porous silicon layers were investigated. The enhancement of intensity of Raman line from porous silicon in comparison with a substrate without any shift of peak position was observed. It is shown that this effect is due to presence of macropores in investigated samples. The enhancement is explained by multiple absorption of probe light scattered and reflected inside macropores while a coincidence of shape and peak position of Raman lines from porous layer and silicon substrate is due to low thickness of nanoporous layer. The method of investigation of porous layer structure based on the combination of Raman scattering effect with variation of probe light wavelength is proposed. (c) 2004 Elsevier B.V. All rights reserved.