Eighty-three of 114 original articles and abstracts of research published by neuropsychiatrists of Chosun Chongdokbu Hospital (the Japanese colonial government hospital in Korea) and Keijō (Seoul) Imperial University Hospital during the Japanese colonial period (1910-1945) in journals including Shinkeigaku-zassi (Neurologia), Seishin-shinkei-gaku zassi (Psychiatria Et Neurologia Japonica), and The Journal of Chosun (Korea) Medical Association were reviewed. Most articles were on clinical research based on descriptive and biological psychiatry while only 4 articles were on dynamic psychiatry, probably because Japanese pioneers in psychiatry had introduced German psychiatry into Japan during the 1880s. The first paper was written by Dr. Shim Ho-sub. Professor Kubo of Keijō (Seoul) Imperial University published most articles, followed by Dr. Hikari, Dr. Hattori, and Dr. Sugihara. There were more articles on symptomatic psychosis and morphine addiction, followed by general paralysis, schizophrenia, neurological diseases, narcolepsy, epilepsy, and neurasthenia. The meaningful articles even for today were comparative studies between Japanese and Koreans and articles on opioid use disorder in Korea. Authors reported a markedly lower rate of psychotic inpatients in the population of Koreans compared with Japanese. Japanese researchers argued that, because of simpleness in social life in Korea and less violence or excitement in symptoms, Korean mental patients could be cared for by family or members of the community, or be treated by shamanism rather than bringing them to a public mental hospital, and poverty also prohibited hospital care. Finding of higher ratio of schizophrenia to manic-depressive psychosis among Koreans than Japanese was discussed in relation to delayed cultural development of Korea compared to Japan. In addition, traditional customs prohibiting marriage between relatives in Korea was related to low prevalence of manic-depressive psychosis, local endemic malaria was related to low prevalence of general paresis, and poor general hygiene was related to high prevalence of epilepsy. Unclear (undifferentiated) form of psychotic symptoms including hallucination and delusion was reported in more Koreans than Japanese. Also Korean patients showed a more atypical form in diagnosis. Authors added that they had found no culture-specific mental illness in Korea. However, no Korean psychiatrists were included as author in such comparative studies. Comparative studies on constitution between Koreans and Japanese mental patients and prisoners were also unique. However, no Korean psychiatrists participated in such comparative studies. In studies on morphine addiction in Koreans, Japanese researchers argued that such studies were necessary to prevent introduction of morphine-related criminal phenomena to Japan. Meanwhile, Dr. Kubo had left a notion on adaptation problems of Japanese living in the foreign country, Korea. Nevertheless he reported nothing about psychosocial aspects of mental illness in relation to political, cultural, and economic difficulties Koreans were experiencing under the colonial rule of Japan. These general trends of studies based on German biological and descriptive psychiatry and policies of colonial government to isolate "dangerous" mental patients in hospital appeared to reflect colonial or ethnopsychiatry of those days. These policy and research trends seem to have worsened stigma attached to mental disorders. Japanese tradition of psychiatric research was discontinued by return home of Japanese scholars with the end of WWII and colonial rule.