After spinal cord injury (SCI) of the cat or rat neuronal centres below the level of lesion exhibit plasticity that can be exploited by specific training paradigms. In individuals with complete or incomplete SCI, human spinal locomotor centers can be activated by appropriate afferent input. This includes to facilitate and assist stepping movements of the legs and to provide body weight support (BWS) standing on a moving treadmill. Individuals with incomplete SCI benefit from such a locomotor training such that they improve the ability to walk over ground. Load- and hip-joint-related afferent input seems to be of crucial importance for both the generation of a locomotor pattern and the effectiveness of the training. It appears to be a critical combination of afferent signals that is needed to generate and improve a locomotor pattern after SCI. Mobility of individuals after a SCI can be improved by taking advantage of the plasticity of spinal neuronal circuits and can be maintained with persistent locomotor activity. Since several years driven gait orthoses can provide a standardized locomotor training. In the future, if regeneration approaches can successfully be applied in human SCI, even individuals with complete SCI may recover walking ability with locomotor training. Presently, individuals with complete SCI, spinal neuronal circuits undergo a degradation of their function 1 year after injury.