A linear-scaling method, based on the definition of a localized molecular orbital set, for the calculation of the electronic structure of a conjugated polymer, is presented and applied to substituted polythiophenes. The ability of this method to predict the localization of the electronic wave function due to structural disorder and to compute the density of states is evaluated. The method is particularly suitable for the analysis of the electronic structure of snapshots deriving from classical molecular dynamics simulations of polymers. We present one such analysis evaluating the effect of inter-chain coupling on the resulting density of states. (C) 2009 Elsevier B.V. All rights reserved.