In present-day Chinese medicine, medical case records or case histories (yi’an) serve an important role in medical education and everyday clinical practice. These are the foremost literary means that enable a student or a practitioner to comprehend the clinical processes of diagnosis and treatment. Surprisingly, we do not find many collections of medical case histories in China before the second millennium CE. More precisely, the genre of yi’an collections became prominent only during the Ming dynasty, for various reasons. It is important to note that the first time a physician published a collection of his medical case histories was during the Song dynasty. In this essay I will delineate the story of the Ninety Discussions on Cold Damage Disorders (Shanghan jiushi lun 傷寒九十論), a collection of medical case histories written and published by Xu Shuwei 許叔微 (1079–1154). Xu applied this innovative approach in his attempt to transmit his accumulated clinical knowledge concerning Cold Damage disorders within the context of the changing medical environment during the Song dynasty. This essay shows why Xu chose to implement this innovative literary means to document medical knowledge.