The structural, electronic and optical properties of LaBr3 have been investigated using the density functional theory within generalized gradient approximation. The calculated structural parameters are in good agreement with the experimental data. The energy band structure, the density of states and atomic charges are obtained, which indicate that the covalent feature of LaBr3 involves the 5p-orbital on La and the 4s-orbital on Br, and that LaBr3 is an insulator with the indirect band gap. Moreover, the optical properties including the dielectric function, absorption spectrum, refractive index, extinction coefficient, reflectivity and energy-loss spectrum are all obtained and analyzed in details within the energy range up to 40 eV. And the results are compared with the available experimental data. (C) 2008 Elsevier B.V. All rights reserved.