Fatigue is a highly prevalent symptom in cancer patients. However in the daily practice this issue doesn't get adequate attention, because of limited therapeutic tools. A number of research issues in this field has been started during the last few years. Some of these new findings will soon modify and improve treatment options. In the meantime it is worthwhile to identify etiologic factors. Some of them might be treated with a reasonable cost/benefit ratio, aiming to improve function and therefore the health related quality of life.