This review describes the types of psychiatric treatment studied during the Japanese colonial period of 1910–1945 in Korea, known at the time as Chosun. Twenty-nine research papers and abstracts on psychiatric treatment were reviewed, which were published in the Shinkeigaku-zassi (Neurologia), the Seishin-shinkei-gaku zassi (Psychiatria Et Neurologia Japonica) and the Journal of Chosun Medical Association, by faculty members of the department of neuropsychiatry, Chosun-Governor Hospital and Keijo (Seoul) Imperial University School of Medicine. The major research area was biological psychiatry and biological treatment, as Japanese pioneers in psychiatry at that time had introduced German psychiatry into Japan. Professor Kubo published the most papers, followed by Dr. Hattori, Dr. Hikari, and Professor Suits. In Chosun-Governor Hospital, research on prolonged sleep therapy was an active field. In the Imperial University Hospital, malarial fever therapy, sulphur-induced fever therapy, and insulin shock treatment were the most frequent research topics. Some were tried for the first time in the Japanese Empire, which reflected the pioneering position of the university. These achievements are attributed to Professor Kubo. Six papers on psychotherapy were published. Among them, two papers were on persuasion therapy, three papers were case reports of psychoanalytic therapy, and one paper on Freud. However, this psychoanalytic therapy research seemed to be limited trials conducted following literal guidance, and no further development was noted. Generally, research was characterized by simple design, small numbers of subjects, lack of objective evaluation method, lack of statistical treatment, and especially lack of ethical consideration comparing with today's standard.