SUMMARY Fatigue in multiple sclerosis is a symptom that is present in up to 95% of patients and has tremendous effects on patients’ quality of life. Often, patients feel impelled to reduce their workload or even to abandon their occupation completely. Not seldomly, these steps lead to social withdrawal and depressive episodes. Although the clinical features and the resulting consequences for patients are well described, objective assessment, quantification of symptom severity and treatment options are still topics of controversial discussion and worldwide accepted methodological approaches have yet to be developed.