The management oft fatigue comprises nonpharmacologic approaches like exercise, cooling procedures, nutrition, and energy conservation programmes. These strategies should be considered as first-line options since they add to overall wellbeing, have no side effects and increase the patient's autonomy. However, in most cases these strategies will not suffice to keep the patient symptom free on the long term. Also, patients with overwhelming and severe fatigue will be unlikely to engage in exercise. In these cases adding pharmacologic therapy will be the next step. Until now, Amantadine, Modafinil, and Pemoline have been used among others, with some success. Also antidepressants like buprione, fluoxetine, and venlafaxine have been used although they have never been systematically studied for the management of MS-related fatigue. However, if a mood disorder is present, it is appropriate to treat it before pursuing pharmacologic therapy of fatigue. Nevertheless, the response rate of all pharmacologic therapies of MS-related fatigue is not totally convincing making alternative pharmacologic therapies furthermore desirable. Methylphenidate is an antagonist of dopamine and norepinephrine transporters on the presynaptic neuronal cell membrane. Reduced reuptake results in an increase in extracellular levels of both neurotransmitters. Until now, methylphenidate has been successfully used to treat fatigue in HIV and parkinson´s disease, data on its efficacy in MS are not available. The aim of this study is to determine the efficacy of methylphenidate treatment in MS-associated fatigue. The treatment phase will be 6 weeks and treatment efficacy will be measured by validated questionnaires (Fatigue Severity Scale FSS, modified Fatigue Impact Scale MFIS) and by a neuropsychological test (Test for Attentional Performance).