Gait impairment in persons with multiple sclerosis (MS) are associated with weakened muscle control, poor coordination, high metabolic demands and fatigue. Robotic exoskeletons may facilitate walking and induce better control during walking leading to coordinated muscle activity, reducing metabolic and cognitive demands. The purpose of this study was to determine the magnitude of variation in cognitive demands in persons with MS during exoskeleton assisted and unassisted walking. Eight subjects diagnosed with MS and expanded disability status scale (EDSS) between 6.0 and 7.5 completed up to 15 sessions of exoskeleton-assisted gait training. After training, cognitive demands were measured by a reaction time (RT) task during Timed 25 feet walk (T25FW). The subjects performed the RT task during both with and without exoskeleton walking. No difference was observed in RT during assisted and unassisted walking. The preliminary findings suggest that individuals with MS could walk with exoskeleton without greater cognitive demands.