Traditional Chinese medicine(TCM),Japanese–Chinese medicine,and Korean Sasang constitutional medicine have common origins.However,the constitutional medicines of China,Japan,and Korea differ because of the influence of geographical culture,social environment,national practices,and other factors.This paper aimed to compare clinical applications and basic studies on the constitutional medicines of China,Japan,and Korea in terms of theoretical origin,constitutional classification,constitution and pathogenesis,treatment,and health care.The constitutional theories of the three countries are derived from the Canon of Internal Medicine or Treatise on Febrile and Miscellaneous Diseases; however,these theories are based on different constitutional classifications and criteria.Medical sciences in the three countries focus on the clinical applications of constitutional theory.Different constitutions are governed by different pathogenic laws that guide the treatment of diseases; thus,patients with different constitutions are treated differently.The three countries focus on health care,which differs based on their constitution.Health care also differs in drug formulations and medication.Japanese medicine is prescribed based on constitution.Korean medicine is based on treatment,in which drugs cannot be mixed.TCM is not limited by prescription and conventional correspondence; TCM is more flexible because treatment is administered on the basis of patients conditions and constitution.Basic studies on the constitutional medicine of the three countries have progressed by gaining knowledge from one another.