Background: One of the biggest problems for persons with Multiple Sclerosis (PwMS) is dizziness, poor posture, and balance problems that cause injury-causing falls. The aim of our study was to reveal the test-retest reliability and validity of the 3-Meter Backward Walk Test (3MBWT) in mildly disabled PwMS. Methods: This study included a total of 93 mildly disabled PwMS with mean EDSS of 1.89. 3MBWT, Functional Access Test (FRT), Dynamic Gait Index (DGI), Timed 25-Foot Walk (T25FW), and Timed-Up and Go (TUG) were applied to the patients. To measure test-retest reliability, a second evaluation was performed three days after the first evaluation. Results: Cronbach's alpha coefficient was found to be 0.998 (excellent). For intra-rater agreement, the ICC values in the individual test were 0.998. The SEM value was 0.18, the MDC value was found to be 0.50. A very strong correlation was revealed between the 3MBWT and FRT (r:-0.931, p: 0.001), TUG (r: 0.968, p: 0.001), T25FW (r: 0.879, p: 0.001), DGI (r:-0.871, p: 0.001) and falling history (r: 0.932, p: 0.001). Conclusion: The 3MBWT was observed to be valid and reliable in mildly disabled PwMS. 3MBWT is an effective and reliable tool for measuring ability to walk backward in mildly disabled PwMS.