Kinematic and functional magnetic resonance imaging were combined to investigate how movement complexity (in-phase vs. anti-phase) and rate (maximum rate vs. 1 Hz) influence the brain sensorimotor network of relapsing- remitting fatigued (F) and not-fatigued (NF) MS patients during the performance of coordinated hand and foot movements.Kinematic measures did not differ between F and NF patients. Task and disease showed an interaction in the right precuneus and posterior lobe of the cerebellum during in-phase/anti-phase conditions and in the right precuneus and posterior and anterior lobes of the cerebellum during maximum vs. 1 Hz rate. Task, disease and fatigue showed an interaction in the right precentral gyrus, the left postcentral gyrus, the left SII, the right precuneus, the right basal ganglia, the left lingual gyrus, and the posterior lobe of the cerebellum, bilaterally, during in-phase/ anti-phase conditions and the left postcentral gyrus, the left SII, the right anterior lobe of the cerebellum, and the posterior lobe of the cerebellum, bilaterally during maximum vs. 1 Hz rate.Investigations of motor task performance in MS patients require careful control of several variables, including task complexity, movement rate, and the presence of "subtle" clinical disturbances, such as fatigue, which might be underestimated at a standard neurological assessment.