Objective: The aim of this study was to characterize the relation between changes in cortical motor commands and the severity of motor and sensory impairment after spinal cord injury (SCI). Design: Prospective. Setting: Outpatient. Participants: SCI subjects and healthy volunteers. Interventions: A 64-channel electroencephalogram was used to record movement related brain potentials from 9 chronic (>2y) SCI subjects and 9 neurologically intact volunteers (controls) while they attempted toe flexion. American Spinal Injury Association (ASIA) motor and sensory score and ASIA impairment scale of each SCI subject were evaluated. Main Outcome Measures: The negative slope, a component of movement related brain potentials preceding the onset of movement was identified and the Center of Cortical Activation (CCA) at the time of peak negative slope was calculated on voltage topographic maps. Difference in location of the CCA in SCI subjects compared with controls was taken as evidence of an altered pattern of motor command generation by the brain. Results: CCAs in SCI subjects were displaced posterior as compared with their location in controls. Step-wise linear regression analysis revealed that the degree of posterior displacement had a statistically significant correlation with the ASIA sensory score (P=.013), but not with the ASIA motor score or the impairment scale. Subjects with greater sensory impairment had a more posterior location of the CCA. The location of the CCA in SCI subjects with ASIA sensory scores below the median (66) for the SCI group was significantly different from that in healthy subjects (P<.05) and SCI subjects with an ASIA sensory score greater than the median (P<.05). Conclusions: Severity of sensory impairment is the major determinant of the extent of alteration in premovement cortical motor commands after SCI.