It is not currently known whether gait and balance measures are responsive to deterioration of motor function in multiple sclerosis (MS) patients with low EDSS scores (≤3.0). The aim of this study was to quantify MS-related gait and balance deterioration over a 12-month period.Thirty-eight participants with MS (33 female, mean age: 41.1 ± 8.3 years), mean time since diagnosis 2.2 ± 4.1 years, EDSS score ≤3.0 and without clinical evidence of gait deterioration, were recruited. Participants performed walking trials and Functional and Lateral Reach Tests. Kinematics of the ankle and knee, and electromyography of the tibialis anterior and medial gastrocnemius muscles were also measured.Three participants reported relapses with worsening EDSS scores and 4 non-relapsing participants had worse EDSS scores at 12 months. There were significant decreases in mean gait speed, stride length and balance scores, and a significant increase in double support. Marked changes in ankle kinematics, with decreased medial gastrocnemius activity were observed.Gait and balance performance of non-disabled RRMS participants may progressively decline, even in the absence of both acute clinical relapse and change in clinical status measured by the EDSS.