Purpose: The purpose of this study was to identify the prevalence of cognitive impairment, behavioral problems, and the state of mental health for elderly Korean people who have been institutionalized. Methods: A cross-sectional, nationwide survey was performed using an anonymous questionnaire. The participants in this study were 2,521 institutionalized elderly Korean people. A proportional stratified random sampling method was employed. Results: 1) Elders admitted to subacute hospitals and long term care (LTC) facilities showed a higher level of cognitive impairment compared to elders admitted to acute care hospitals. 2) Elders confined in LTC facilities showed a higher level of behavioral problems compared to elders in acute or subacute hospitals. 3) Elders admitted to subacute hospitals and LTC facilities showed more serious mental health problems, such as depression or suicidal ideation, compared to elders in acute care hospitals. Conclusion: The results of this study indicate that the severity of cognitive-behavioral or mental health problems do not match well with type of care setting. Therefore, health personnel working with elderly people should be provided guidance on detection and management of cognitive-behavioral and mental health problems. The necessity of a decision support system for eligibility and placement in long-term care is also discussed.