ObjectiveTo assess the effects of an 8-week aquatic exercise training program on functional capacity, balance, and perceptions of fatigue in women with multiple sclerosis (MS). DesignRandomized controlled design. SettingReferral center of an MS society. ParticipantsWomen (N=32; mean age ± SD, 36.4±8.2y) with diagnosed relapsing-remitting MS. After undergoing baseline testing by a neurologist, participants were allocated to either an intervention (aquatic training program, n=17) or a control group (n=15). InterventionsThe intervention consisted of an 8-week aquatic training program (3 supervised training sessions per week; session duration, 45–60min; 50%–75% estimated maximum heart rate). Main Outcome MeasuresSix-minute walk test (6-MWT), balance (Berg Balance Scale [BBS]), and perceptions of fatigue (Modified Fatigue Impact Scale; [MFIS]) at baseline and after the 8-week intervention. Differences over time between the experimental and control groups were assessed by a 2×2 (group by time) repeated-measures analysis of variance. ResultsThirty-two women completed the 8-week aquatic training intervention (experimental group, n=17; control group, n=15). All outcome measures improved in the experimental group: 6-MWT performance (pretest mean ± SD, 451±58m; posttest mean ± SD, 503±57m; P<.001); BBS (pretest mean ± SD, 53.59±1.70; posttest mean ± SD, 55.18±1.18; P<.001), and MFIS (pretest mean ± SD, 43.1±14.6; posttest mean ± SD, 32.8±5.9; P<.01). A significant group-by-time interaction was evident between the experimental and control groups for 6-MWT (P<.001, partial eta2 [ηp2]=.551), BBS (P<.001, ηp2=.423), and MFIS (P<.001, ηp2=.679). ConclusionsAquatic exercise training improved functional capacity, balance, and perceptions of fatigue in women with MS.