Diarylethenes are a class of photochromic molecules whose conductance switches with their photoisomerization. We have investigated the conductance of diarylethenes using non-equilibrium Green's function method combined with Huckel method (NEGF-HMO) and density functional theory (NEGF-DFT). In this study we have found that the qualitative predictions based on frontier orbital analysis are consistent with the DFT calculations and can be used for prediction of the electron transport properties of molecular devices. (C) 2009 Elsevier B.V. All rights reserved.