We report calculations on the CH3D + O(P-3) > CH3 + OD reaction using a reduced dimensionality model with four degrees of freedom. The model has already been used to evaluate the effect of the symmetric and asymmetric stretching vibrations of methane on the CH4 + O(P-3) and CH4 + H reactions. Unfortunately, it is not easy to establish a direct comparison between these previous calculations and experimental results. As the difficulties disappear when CH4 is replaced with CH3D we decided to try our model on the title reaction. The results of these new calculations are presented in this Letter. (C) 2002 Elsevier Science B.V. All rights reserved.