Monte Carlo simulations were employed to investigate the effective thermal conductivity of carbon nanotube-polystyrene (CNT-PS) nanocomposites at different wt.% of CNT loadings and temperatures. By validating with experimental data, values of phonon transmission probability as well as Kapitza resistance at the CNT-PS interface and at the CNT-CNT contact were calculated. In addition, the observed poor enhancement of thermal conductivity at high CNT concentrations was found to be the result of the CNT-CNT thermal resistance and of the bundle configuration. (C) 2011 Elsevier B. V. All rights reserved.