A mysterious disease was first reported from Korea when it had been observed during late spring 1951 in UN Forces operating in the central area close to the 38th parallel. The disease showed distinctive features which included high fever, low blood pressure, hemorrhagic tendency and acute renal failure. Historically it was apparently a similar disease to a clinical entity designated as Epidemic hemorrhagic fever in Manchuria or Hemorrhagic nephrosonephritis in Far Eastern Russia. After Lee Ho-Wang succeeded in demonstrating Hantaan virus which caused hemorrhagic fever with renal syndrome (HFRS), many studies has revealed various biological and epidemiological aspects of the disease. But the origin of the disease in Korea still remains unknown. This article tests some hypotheses which explain the origin of the disease and reviews the relation between the Korean War and HFRS. It is concluded that the emerging of HFRS would be closely related with the establishment of the munitions supply network in early 1951 in Chinese troop.