Fragment molecular orbital (FMO) method, which has been proposed and tested to investigate electronic properties of large molecular systems for Hartree-Fock theory, is combined with density functional theory (DFT) to include the electron correlation effect. The convergence acceleration technique with direct inversion iterative subspace method is implemented for efficiently obtaining self-consistent field electron charge in the FMO framework. We numerically confirm the validity of this FMO-DFT method using some model systems. (C) 2003 Elsevier B.V. All rights reserved.