The aim of this study was to evaluate if the effect of longer training times (50 instead of 25 minutes per day) using a robotic device results in a better outcome of walking ability of subjects with a sub-acute motor complete (AIS B) and incomplete (AIS C) spinal cord injury (SCI). Twenty-one patients were enrolled in the study whereof, 18 completed on average 34 trainings in eight weeks. Longer training times resulted in better locomotor function. The second important result of the study is that a beneficial effect can be achieved by the application of a robotic device for prolonged training sessions without requiring more personal resources. It has to remain open whether even longer training times (more than 50 min) would result in a still better outcome. In any case, the extent of possible recovery in an individual patient is determined by the level and severity of spinal cord damage.