Objective: The purpose of this study was to establish the prevalence of PTSD among North Korean defectors who visited the National Medical Center, Seoul, South Korea over a period of approximately 10 years by examining their medical records and to examine differences in the medical service usage patterns of patients with and without PTSD. Methods: Data from North Korean defectors who used outpatient services at the National Medical Center during a period of 10 years and 3 months (January 1 2006 to February 28, 2016) were analyzed. The general characteristics of the defectors were analyzed by frequency analyses, and descriptive statistics were generated. Additionally, independent t-tests and chi square analyses were performed to examine differences between PTSD patients and those without PTSD. Linear regression analysis was performed to examine factors affecting the mental health of North Korean defectors suffering from PTSD. Results: This study assessed the correlations between PTSD, the average number of outpatient visits, and the total revenue. The regression analysis showed a relationship between PTSD and the average number of outpatient visits. There was also a correlation between PTSD and total revenue. The average number of outpatient visits was 41.8 for PTSD patients, whereas it was 33.2 for those without PTSD. The total revenue visit was 953.6 USD for PTSD sufferers and 231.1 USD for those without PTSD. Conclusion: This study found that the majority of North Korean defectors visit psychiatry departments, and that PTSD patients use outpatient services more frequently and have higher total revenue than those without PTSD. Additionally, patients with PTSD used a greater variety of medical services. Considering the high medical care expenses of North Korean defectors residing in South Korea, future investigations should examine the medical service usage patterns of such patients, especially those diagnosed with PTSD, in greater detail.