Background and Aim: The initial concept that is extracted from the term "Weakness" is unpleasant condition with a reduction or lack of physical and mental powers that impede the normal and desired outcomes. Weakness in this concept is a common phenomenon and has serious effects on the quality of individual and social life. Today, the field of health is faced with many challenges in identifying and determining the causes of Weakness. The study of traditional medicine with the support of ancient knowledge opens new horizons to us for Weakness. The aim of this study is to investigate the types of Weakness and its causes in the ancient texts of traditional medicine. Materials and Methods: This study was conducted in the main texts of traditional medicine using the "Noor" software by weak and Weakness keywords. The search engines Up to date, SID, Magiran, PubMed, Scholar and Scopus were reviewed with Weakness and fatigue keywords. Conclusion: In terms of definition and symptoms fatigue and organ failure agree with general body Weakness and functional Weakness of organs. Considering the causes of Weakness in traditional medicine, we can present new solutions in general and special (functional) Weakness.