Objective The aim of this study was to estimate the prevalence of major psychiatric disorders among North Korean defectors (NKD) settled in South Korea.Methods The study population consisted of 294 North Korean defectors, aged 18 to 64 years settled in South Korea for 3 years or less. Between June 1, 2016 and October 31, 2016, face-to-face interviews were conducted using the North Korean version of the WHO-Composite International Diagnostic Interview (NK-CIDI) to diagnose DSM-IV psychiatric disorders.Results The lifetime prevalence of any DSM-IV psychiatric disorders was 62.2% in NKD and 25.0% in the general Korean population. The prevalence of specific disorders in NKD and general Korean population was as follows: 22.3% and 4.9% for major depressive disorder (MDD), 12.2% and 1.4% for post-traumatic stress disorder (PTSD), 18.0% and 4.8% for nicotine dependence, and 14.5% and 11.2% for alcohol abuse. The incidence of every single psychiatric disorder varied in each country. For instance, the generalized anxiety disorder, specific phobia, and alcohol use disorder occurred more frequently in North Korea whereas PTSD was more prevalent in other countries.Conclusion The prevalence of psychiatric disorders among NKD was quite higher than in the general population of South Korea.