Objectives: Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system that is the second leading cause of nerve failure in young adults. One of the clinical manifestations of MS is impaired balance and gait. Ankle-foot Orthosis (AFO) and Functional Electrical Stimulation (FES) are the most common rehabilitation interventions to improve the patients’ gait and balance. This study aimed to evaluate and compare the effect of using an FES system and an AFO equipped with FES on the gait and balance of patients with MS. Methods: This research was a cross-sectional study. The patients were included in the study who were diagnosed with MS, had a score of lower than five on the expanded disability status scale, had a history of drop foot for at least three months, aged 20-50 years, and prescribed an AFO or FES, or both. The participants were asked to wear the FES system to evaluate their balance and ability to walk using the Balance Evaluation Systems Test (BESTest). Then, the participants were asked to wear an AFO equipped with FES, and their balance and ability to walk were assessed again. Results: The AFO equipped with FES provides more gait stability than FES alone condition (P <0.05). The ability of patients to use the FES alone was greater than using the AFO equipped with FES (P<0.05). Discussion: The study results showed that the walking ability of MS patients using an FES system is greater than that of AFO equipped with FES. This outcome can be due to the difficulty and limiting effect of using an orthosis on their performance. However, the patient’s postural response during stepping back and forth in the condition of AFO equipped with the FES system was better than the FES system alone.