Purpose : This study aimed to investigate the prevalence and risk factors of mental health problems in patients discharged from the intensive care unit (ICU). Methods : This was a secondary analysis study using data from a multicenter prospective cohort of post-ICU patients. We analyzed data of 311 patients enrolled in the primary cohort study who responded to the mental health questionnaire three months after the discharge. Anxiety and depression were measured on the Hospital Anxiety-Depression Scale, and post-traumatic stress disorder (PTSD) was measured on the Posttraumatic Diagnostic Scale. Results : The prevalence of anxiety, depression, and PTSD in patients at three months after ICU discharge were 25.7%, 17.4%, and 18.0%, respectively, and 7.7% of them experienced all three problems. Unemployment (OR=1.99, p=.033) and unplanned ICU admission (OR=2.28, p=.017) were risk factors for depression, while women gender (OR=2.34, p=.009), comorbid diseases (OR=2.88, p=.004), non-surgical ICUs (trauma ICU: OR=7.31, p=.002, medical ICU: OR=3.72, p=.007, neurological ICU: OR=2.95, p=.019) and delirium (OR=2.89, p=.009) were risk factors for PTSD. Conclusion : ICU nurses should proactively monitor risk factors for post-ICU mental health problems. In particular, guidelines on the detection and management of delirium in critically ill patients should be observed.