Approximate density functional theory (DFT) covers long-range non-dynamic electron correlation via the exchange functional while the correlation functional includes just the short-range dynamic electron correlation effects. We show that the self-interaction error of approximate exchange functionals (local density approximation. LDA and others) mimics the long-range correlation effects. For this purpose the exchange hole is investigated at the Hartree-Fock. the LDA, and the self-interaction corrected (SIC)-LDA levels of theory, (C) 2002 Elsevier Science B.V. All rights reserved.