Ex vivo diffusion tensor imaging (DTI) was used to study the effects of motor training on interhemispheric connectivity after ischemic stroke in mice. Training increased the number of fibers of the corpus callosum by one third. No overall effect of lesion size on DTI parameters and general interhemispheric connectivity was observed. Trained animals with large lesions, however, had higher fiber counts and axial diffusivity compared to non-trained animals with similarly large lesions. A larger benefit of motor training on animals with more severe stroke is implied.