Gwan-Gyeok(關格) is one of the dangerous conditions that can lead to death and is considered important in clinical practice. However its true concept is unclear and arguments on the subject have been diverse over generations. This kind of confusion is largely due to an insufficient understanding of the study results on Nangyeong(難經). In Nangyeong, Gwan-Gyeok is divided into ‘in bowels(在腑)’ and ‘in viscera(在臟) and distinction is made between ‘damaged by heat(傷熱)’ and ‘damaged by dampness(傷濕) thus establishing a broad outline of differentiation of syndrome(辨證). Moreover, the clinical progress is systematically divided into 3 stages thus providing a very useful viewpoint on diagnostics. A sharp perspective on the pathogenesis is also shown by emphasizing the kidney and Myeongmun(命門) through the comparison between cheok pulse(尺) and chon pulse(寸). This point of view in Nangyeong is truly proposing a permanent standard on the understanding of Gwan-Gyeok. Therefore it is the author’s hope that this study will work as a start to look back on the flow of the research on Gwan-Gyeok which has been rather confusing since Sanghallon(傷寒論).