Objectives: This study aimed to develop a health needs assessment (HNA) tool for persons with brain disorders and to assess the unmet needs of persons with brain disorders using the developed tool. Methods: The authors used consensus methods to develop a HNA tool. Using a randomized stratified systematic sampling method adjusted for sex, age, and districts, 57 registered persons (27 severe and 30 mild cases) with brain disorders dwelling in Seoul, South Korea were chosen and medical specialists investigated all of the subjects with the developed tools. Results: The HNA tool for brain disorders we developed included four categories: 1) medical interventions and operations, 2) assistive devices, 3) rehabilitation therapy, and 4) regular follow-up. This study also found that 71.9% of the subjects did not receive appropriate medical care, which implies that the severity of their disability is likely to be exacerbated and permanent, and the loss irrecoverable. Conclusions: Our results showed that the HNA tool for persons with brain disorders based on unmet needs defined by physicians can be a useful method for evaluating the appropriateness and necessity of medical services offered to the disabled, and it can serve as the norm for providing health care services for disabled persons. Further studies should be undertaken to increase validity and reliability of the tool. Fundamental research investigating the factors generating or affecting the unmet needs is necessary; its results could serve as basis for developing policies to eliminate or alleviate these factors.