Abstract
Objectives Syndrome differentiation and treatment (辨證論治) was one of the core theories in Korean medicine and syndrome differentiation (辨證) constitutes a branch of disease diagnosis in Korean medicine. Yoon Gil-Young, one of the modern outstanding scholar of basic medical science in Korean medicine, wrote on basic theories of Korean medicine such as physiology, pathology, formula science, etc. Hereby we will analyze and discuss his works to understand his recognition of historical changes in the syndrome differentiation. Methods We conducted researches into the two works of Yoon Gil-Young's, which are "The Clinical Formula Science of Eastern Medicine (東醫臨床方劑學)" and "The theory of Four-Constitution Medicine (四象體質醫學論)". From Yoon's academic standpoint which connects the basic medical science with the clinical medicine, we analyzed his opinion about the system in the Theory of 'Syndrome Differentiation'. Results According to Yoon's research work on the Theory of 'Syndrome Differentiation', the system of syndrome differentiation, which had its deep root in the theory of Yin and Yang (陰陽) & the theory of abbreviation of the five circuit phases (五運) and the six atomspheric influences (六氣) of the "Huangdi's Internal Classic (黃帝內經)". Conclusions Yoon Gil-Young's theory of differentiation of syndromes and treatment is widespread so much that he studied on the learning field of Traditional Korean Mediciine and ingenious as well. He explain on the main principles of differentiation of syndromes based on "Huang Di Nei Jing" and the system of differentiation of syndromes is composed of Traditional Korean Medical Physiology.