Cancer-related fatigue (CRF) is a subjective, frequent condition of physical, affective and cognitive tiredness and exhaustion, which has a negative impact on every-day-activities, quality of life and overall survival. To reduce the risk of chronification, CrF should be recognized and treated early. (Differential-) diagnosis can be made by a structured anamnesis, CrF-self-evaluation questionnaires and using the proposed diagnostic criteria of the former Fatigue Coalition for admission to the ICD 10. To treat CrF symptomatically, treatment options with evidence from randomized controlled clinical trials (RCT), systematic reviews and meta-analysis are available.