Most people experience fatigue at some point in their lives, and they say the word 'fatigue' in their ordinary conversational speech. The ordinary word is used as a military or engineering term and has been studied in various different disciplines such as ergonomics, physiology, psychology, medicine, and nursing. In spite of its widespread uses, however, fatigue has not been well defined. The terms of fatigue is thus often used with different meanings and is applied in diverse contests that had led to a confusion of ideas. In people with cancer, fatigue is reported as a major distress. Despite the importance of fatigue in cancer patients, the phenomena of fatigue is poorly understood. Therefore, the purpose of the present study is to analyze the concept of fatigue in people with cancer. The process for the concept analysis was guided by Walker and Avant's conceptual analysis methodology. The identified attributes of fatigue in the present study were subjective feeling, lack of energy, sustenance, and multi-dimensions. The antecedents were cancer treatment and economic status. The consequences were decreased daily, vocational, leisure, and social activities, uncertainty, and difficulties in adjustment. Symptoms(pain, anorexia, and insomnia) and emotional disturbance were not clear whether they are antecedents or consequences. However, they are related with cancer related fatigue. Even though still in the beginning stage, instruments measuring cancer related fatigue have been developed by some nursing investigators.