Abstract Raman spectroscopy is a promising method for optical vibrational spectroscopy. Nowadays, Raman spectroscopy finds many applications, in particular, in biological and medical diagnostics. However, the Raman scattering can be enhanced using the Surface-enhanced Raman scattering method. Colloidal solutions of noble metals are used as SERS-active systems. In this work, the enhancing factors were estimated for colloidal silver solutions of three different types (citrate, borohydride, chloride) with two substances (phenylalanine, cytochrome C). Phenylalanine is a widely used model substance for Raman and Surface-enhanced Raman spectroscopy. Cytochrome C is one of the most researched proteins. It involves in the electron transport chain of the mitochondrial inner membrane and provides cellular respiration. Borohydride, citrate and chloride sols with phenylalanine gave an enhancement about 50, 200 and 30 times, respectively, and with cytochrome C about 30, 160 and 20, respectively. A comparative analysis of active and inactive sols by SERS and absorption spectroscopy was also performed. The absorption spectra of active sols have characteristic maxima in the region of 400 nm. Both the SERS method of model substances and absorption spectroscopy can be used to assess the enhancing properties.