We report the result of calculation of the quasiparticle thermal conductivity kappa(xx)(del T perpendicular to B) in the vortex state of a two-dimensional superconductor. We compute k(xx) for both s-wave and d-wave superconductors, taking account of the spatial dependence of normal Green's function g, which is neglected in the previous studies using the Brandt-Pesch-Tewordt (BPT) method. Our results indicate that k(xx) based on the BPT method is slightly underestimated due to its incoherent spatial averaging procedure. (c) 2006 Elsevier B.V. All rights reserved.