KyungBoSinPyun (輕寶新篇), preserved at the KIOM(Korea Institute of Oriental Medicine), is a historical medical text containing 142 examples of “Yi’an” (醫案), an East Asian tradition of describing clinical encounters with the therapies employed. Despite rising interest in “Yi’an”, up until now KyungBoSinPyun has remained hidden and mysterious. This study, the first professional research into KyungBoSinPyun, focuses particularly on “Yi’an” from three points of view: bibliographic, historical and medical. From a bibliographic perspective, it is assumed that KyungBoSinPyun, a handwritten text, was produced in the early 20th century in the southern province of Korea by Lee, Gyogook (李喬局), although it is uncertain whether that is the name of a person or a pharmacy. Following the primary historical stream of Korean medicine after the publication of Donguibogam (東醫寶鑑), a compilation of medical knowledge edited by Heo Jun (許浚) in 1613, KyungBoSinPyun is located within the context of the medical trend of the late Joseon (朝鮮) Dynasty(1392-1910), characterized by authors’ writing medical books based on Donguibogam and adding their successful medical experiences. KyungBoSinPyun, however, is unique in that using forms of “Yi’an” to write about experiences was a very rare phenomenon in the history of Korean medicine. Many of the prescriptions described in the “Yi’an” of KyungBoSinPyun are very similar to featured prescriptions in Donguibogam. In particular, the frequent application of tonifying methods (補法) is a distinctive characteristics of this book. KyungBoSinPyun illustrates the reality of clinical encounters during the late Joseon Dynasty and shows Donguibogam therapies applied in real life, which makes KyungBoSinPyun a valuable historical records.