This report describes characteristics of patients who had high out-of-pocket (OOP) spending on mental health care relative to income.A sample of 8,923 U.S. adults with outpatient mental health visits was drawn from the 2018-2021 Medical Expenditure Panel Survey. Respondents who spent ≥10% of their disposable family incomes on OOP mental health visits were defined as having a high OOP cost burden.Using weighted percentages, the authors found that 2.4% of psychiatric outpatients had a high OOP burden; among those below the federal poverty level, 12.8% had a high OOP burden. Patients with a high (vs. low) OOP burden were statistically significantly more likely to be uninsured (7.5% vs. 2.4%) or diagnosed as having a substance use disorder (8.7% vs. 2.8%) or bipolar disorder (14.5% vs. 8.0%).Despite federal policies extending the availability of insurance for mental health care, many low-income psychiatric outpatients experience high OOP cost burden.