Two-state model is commonly used to estimate the donor-acceptor electronic coupling V-da for electron transfer. However, in some important cases, e.g. for DNA pi-stacks, this scheme fails to provide accurate values of V-da because of multistate effects. The Generalized Mulliken-Hush method enables a multistate treatment of V-da. In this Letter, we analyze the dependence of calculated electronic couplings on the number of the adiabatic states included in the model. We suggest a simple scheme to determine this number. The super-exchange correction of the two-state approximation is shown to provide good estimates of the electronic coupling. (c) 2006 Elsevier B.V. All rights reserved.