BACKGROUND Exercise may have beneficial effects in MS, remaining controversial its possible disease-modifying effects and which mechanisms might be involved. We evaluated whether exercise-induced lymphocyte redistribution differ in MS patients as compared to controls. METHODS Exercise was assessed in 12 relapsing-remitting MS patients and 11 controls in a cycle ergometer, obtaining blood samples before exercise, at maximal exercise capacity (T1), and after resting (T2). Peripheral lymphocytes were evaluated by flow cytometry, assessing chemokine receptor expression to study cell trafficking properties. RESULTS Lymphocyte subsets in all cases increased after exercise and decreased at resting. However, total natural killer (NK) cells in patients as compared to controls had a lower exercise-induced redeployment at T1 (696 ± 581 cells/µL vs.1502 ± 641 cells/µL, p < 0.01). Evaluating NK cell subsets, CD56bright NK cells numbers decreased in peripheral blood in MS patients after resting (T2), contrasting with values remaining above baseline in healthy controls. NK cells mobilized after exercise at T1 in controls, as compared to patients, had a higher CX3CR1 expression (1402 ± 564/µL vs. 615 ± 548 cell//µL, p < 0.01). CONCLUSIONS Exercise-induced redeployment of NK cells may be reduced in MS patients, as well as their migration capabilities, pointing to potential immunological mechanisms to be enhanced by exercise training programs.