OBJECTIVE: A lot of research has been conducted on cancer related fatigue over the last ten years. In this paper I have reviewed some of the most important aspects of epidemiology, quality of life, patophysiology and treatment options. A special focus is on Breast Cancer. METHODES: A series of thorough searches of pubmed and cochrane database using the terms ”Cancer Related Fatigue (CRF)”, ”fatigue”, ”treatment”, ”epidemiology”, ”quality of life”, ”Breast Cancer” and ”Neoplasm.” I have also looked over other review-articles to find articles that I might have missed in my own searches. CONCLUSION: About 30 % of breast-cancer patients experience chronic cancer related fatigue after having finished their treatments. This is persistent for months to years, and affects their overall quality of life. Several hypotheses on patophysiological mechanisms have been looked in to, but there is no conclusive evidence to one theory. Non-pharmacological treatment is still preferred, but a lot of research is being performed on pharmacological options.