A new method to compute high quality electron densities of polypeptides is proposed. The method is based on the transferability properties of extremely localized molecular orbitals, which can be used to describe with great accuracy the different functional groups of a molecule. It is then possible to generate a database of such orbitals, each of them associated with specific amino acids and with the peptide bond. A new program, named DENPOL, has been written aimed at using this database to build up the electron density of a generic polypeptide. Due to both the large number of orbitals required to describe a polypeptide and the non-orthogonal nature of these orbitals, a Divide & Conquer strategy has been used to assemble the final electron density. The application of this strategy is particularly efficient thanks to the extreme localization of the orbitals. The comparison with the corresponding electron densities generated by the Hartree-Fock method, shows the goodness of the proposed approach and indicates that the electron densities generated by DENPOL are very close to those generated by an ab initio approach.