This document is Korea’s oldest Western-style diagnosis issued to C. A. Welsch, a customs officer, on September 13, 1885 by H. N. Allen (1858-1932), who was appointed as the director of the first modern hospital in Korea. The diagnosis states that the patient required treatment for one to two weeks. Allen came to Korea in September 1884 as an American missionary and started working as a medical doctor entrusted by the American Legation in Korea. At his recommendation, the Jejungwon Infirmary (House of Universal Helpfulness) was founded in 1885 as the first Western medical institution, and he served its head between April 1885 and September 1887. Later, he switched career and assumed leadership of the American Legation in Korea.