Methods to determine the electronic structure of atoms and molecules are crucial for a reliable description of complex chemical processes that are inaccessible to conventional empirical models. Standard quantum mechanical techniques are limited to fairly small molecular systems due to unfavorable scaling properties inherent in the computational algorithms. We report the application of a recently developed linear-scaling quantum mechanical method to the study of aqueous polarization effects on biological macromolecules. The polarization contribution to the solvation free energy is in the range of 5 - 15% for proteins and 1 - 3% for DNA. Results suggest that polarization of proteins and DNA in the process of solvation can be well approximated by a linear response model. The developments presented here extend the realm of quantum chemical techniques to applications of macromolecular systems in solution.