Fatigue is a common symptom in patients with cancer and in disease-free survivors. It has a significant impact on the quality of life. Although subjective fatigue is often related to objective changes in physical functioning or impaired performance status, the two phenomena are not synonymous and need to be distinguished. A number of robust and reliable assessment instruments to measure fatigue severity are now available and criteria for cancer-related fatigue syndrome have been proposed. The underlying mechanisms and pathophysiology of cancer-related fatigue are unclear. Management strategies include the use of psycho-educational interventions, exercise programmes and pharmacological treatments. The best evidence for the effectiveness of drug treatments is for the haematopoietic agents in anaemic patients undergoing chemotherapy and for methylphenidate in an on-treatment population.