This paper examines the role of League of Nations Health Organization in shaping leprosy control in colonial Korea and East Asia. In 1931, the Japanese colonial government in Korea announced the formation of Chosen Leprosy Prevention Association. Shortly after the colonial government made the announcement, the Government of Japan revised the 1907 segregation law and the establishment of leprosy prevention association. Called Japan Leprosy Prevention Association, the association had been modeled after the British Empire Leprosy Relief Association (BELRA). With colonial Korea and Japan proper passing legislation, in Taiwan, the Japanese colonial government made the announcement of government leprosarium in 1933. To scholars working on East Asian history of leprosy, the year 1931 was the pivotal moment when compulsory leprosy began in the empire. This paper proposes new reading of the 1931 leprosy activities in East Asia by exploring the involvement of Kiyoshi Shiga, the discoverer of dysentery bacillus, in the Leprosy Commission of the League of Nations Health Organization from 1926 to 1931. At the time, the dean of faculty of medicine at the Keijo Imperial University, the colonial university in Korea, Shiga was asked by Ludwik Rajchman, the head of LNHO in 1926, to join the newly established expert committee on global leprosy eradication control. The LNHO activities in those years resulted in the first world survey of leprosy and principles on prophylaxis of leprosy, one of very first attempts to standardize leprosy treatment in 1931. By studying Shiga’s involvement in the Leprosy Commission, the argument of this paper is that East Asian history of leprosy, in particular, the year of 1931 has to be reconsidered in the context of the international health movements that were taking place in the interwar years (1919 ~ 1941) around the world. By showing the connection between Shiga’s activities in colonial Korea to the League of Nations, ultimately, the conclusion here is that modern health and medicine in Korea, Taiwan and Japan cannot be simply understood as legacy of Japanese colonialism, but as result of exchanges and interactions with actors, agencies and movements within the larger international health and medical activities of the interwar years.