The National Health Insurance (NHI) database in Taiwan was used to detect the use of health care services and the costs of psychiatric disorders among NHI enrollees. Data were analyzed for 126,146 enrollees. Four categories were used for enrollees: no psychiatric disorder, a minor psychiatric disorder, a major psychiatric disorder without catastrophic illness registration, and a major psychiatric disorder with catastrophic illness registration (which eliminates copayments). Compared with enrollees with a minor psychiatric disorder, those with a major psychiatric disorder, either with or without catastrophic illness registration, had higher use and costs of mental health care services. Compared with enrollees without a psychiatric disorder, those with a minor psychiatric disorder or a major psychiatric disorder without catastrophic illness registration had higher use and costs of non-mental health care services. Both the mental and general health care of persons with psychiatric disorders are important.