 Recent studies have provided strong evidence that motor recovery after adult ischemic stroke is a function of neural plasticity. Up to date, it remains largely unknown as to the relationship between the integrity of the subcortical white matter with the lower extremity function recovery. Given the fact that the white matter is more resistant to ischemia after acute stroke than the gray matter Falcao et al., 2004 and that the intensity of white matter in stroke has been found to be much greater in many brain areas in stroke than in healthy controls Wen et al., 2004, it is of interest to study how the integrity of the subcortical white matter, primarily the corticospinal tracts and the corpus callosum, contributes to the recovery of lower extremity function in subacute and chronic stroke with lesions involving different areas of the brain. 