Introduction: Widespread cerebral hypometabolism occurs in multiple sclerosis (MS) which can result in cognitive dysfunction. The purpose of this study was to determine the effects of a 7-day water aerobics exercise intervention on the cerebral hyperemic response to a cognitive task in individuals with MS. Methods: Thirty-one individuals diagnosed with MS were assigned to an exercise group (N = 17) or a control group (N = 14). For 7 days, the control group maintained normal activity, while the exercise group participated in water aerobic exercise. Oxygenated hemoglobin (O2Hb) was measured using nearinfrared spectroscopy at rest and during a cognitive task prior to and after the 7 day period. Results: For the exercise group, there was no significant difference between O2Hb from rest to cognition at pre-testing (t(16) = -1.91, p = 0.07), however O2Hb significantly increased from rest during cognition at post-testing (t(16) = -2.30, p = 0.04). For the control group, O2Hb significantly increased from rest during cognition at pre-testing (t(13) = -2.51, p = 0.03), but did not at post-testing (t(13) = -1.6, p = 0.13). Conclusions: Water aerobics exercise could be a useful therapy for improving the cerebral perfusion in individuals with MS.