The Republic of Korea(ROK) and the World Health Organization(WHO) have done many projects successfully from 1949, in which the government of First Republic joined the WHO. However the relation between the ROK and the WHO have not been studied very much so far. The main purposeof this research, which could be done by the support of WHO, is connected with three questions. First research point would be “how could the ROK joined WHO in 1949 and what’s the meaning of it? And the what’s the difference in the processfor the WHO between the ROK of 1949 and the DPRK(Democratic People’s Republic of Korea) of 1973?” The first president of the ROK, Rhee Syngman,who had received his Ph. D.(about international politics) from Princeton University in 1910, was strongly interested in joining international institutes like UN, WHO. The ROK that could join WHO on 17 August 1949, with the approval of Assembly on 25 May 1949, was one of the founder membersof the Western Pacific Region. By joining WHO, the ROK could get chance to increase the level of public health and its administration in 1950’s. Butthe DPRK manage to became a member of WHO on 19 May 1973 andjoined the South-East Asia Region. The joining of DPRK was influenced by the easing of the cold war after the Nixon Doctrine and the joining of the China(People’s Republic of China). Second research point would be “What kind of roll did the WHO takein the First Republic?” Yet the public health administration of the First Republic that had been made in the period of US army military government was been strongly influenced by USA, the roll of WHO was also importantin the 1950’s. Last research point would be “What kind of the projects did the ROK and the WHO take part in during the period of he First Republic? How could evaluate the results?” The ROK and the WHO handled the projects including health services, communicable disease prevention and control,control of noncommunicable diseases, and protection of health. Specially for the efforts to prevent communicable disease, the WHO focused on leprosy, malaria, measles, smallpox, tuberculosis in 1950’s. The First Republic could overcome the bad health condition after the Korea War successfully, supported by WHO.