慢性疲劳（倦）症候群（英语：chronic fatigue syndrome, CFS）是一种身体出现慢性疲劳征状的病症，具体定义是长期间（连续6个月以上）原因不明的强度疲劳感觉或身体不适。现时人类对这种病的认识仍然很少，病理学成因不明。绝大部分的患者都与工作紧张与压力过大，以及长期生活作息不正常等有关；若长期任由身心疲累，没有好好调养，可能会引发一些危险因子，从轻微的「疲劳」演变成严重的「过劳」。

Chronic fatigue syndrome (CFS) is a complex medical condition, characterized by long-term fatigue and other symptoms. These symptoms are to such a degree that they limit a person's ability to carry out ordinary daily activities. Quality of life of persons with CFS can be compromised.