We examined changes in state anxiety (SA) and Total Mood Disturbance (TMD) associated with acute exercise in persons with multiple sclerosis (MS) and the influence of trait anxiety (TA) on the magnitude of the changes. Females (N=25) with MS were separated into subgroups of higher trait anxiety (HTA, n=8) or lower trait anxiety (LTA, n=17). Participants completed an incremental exercise test to measure VO(2peak), and on a separate day completed the trait and state portions of the State-Trait Anxiety Inventory (STAI; Forms Y1 and Y2) and the Profile of Mood States (POMS) before performing 20 minutes of cycle ergometry at 60% of VO(2peak). Participants completed the state portion of the STAI (Form Y1) and the POMS at 5, 20, and 60 minutes after exercise. There were large reductions in SA 5, 20, and 60 minutes after exercise in the HTA group, and SA scores were relatively unchanged in the LTA group. There were large reductions in TMD 5, 20, and 60 minutes after exercise in the HTA group, and small reductions in TMD 20 and 60 minutes post-exercise in the LTA group. Moderate-intensity cycling exercise was associated with reductions in SA and TMD in persons with MS, and changes were larger in individuals reporting higher TA.