This article examines the care provided for the welfare of soldiers by the three combatant countries – China, Korea and Japan – during the East Asian War of 1592–8. Also known as the Imjin War, this large-scale military conflict can also be understood as an encounter between different state cultures and strategies of military medicine. This study focuses on cold-induced injuries, epidemic outbreaks and external wounds suffered during the war. I illuminate provision of prophylactic measures against cold by the Ming state, as well as attempts by the Sino-Chosŏn medical alliance to manage epidemics and treat wounded soldiers. I contrast these measures with the lack of similar centralised support for the Japanese forces, and examine the effect these differences had upon on military outcomes during the war. The difference in the amount of time, efforts and resources that the three combatant states devoted to sick and injured soldiers has implications not only for our understanding of the war but also for illuminating the early modern history of military medicine in East Asia. By exploring East Asian military medicine during and after the Imjin War, this article responds to recent calls for more detailed examination of histories of military medicine in premodern periods and non-European regions.