Objective: We investigated whether mental illness is associated with lower rates of CEA/CAS after stroke due to carotid stenosis. Methods: In this retrospective cross-sectional study, ischemic stroke cases due to carotid stenosis were identified in the 2007-2014 Nationwide (National) Inpatient Sample. Psychiatric conditions were identified by secondary ICD9-CM diagnosis codes for schizophrenia/psychoses, bipolar disorder, depression, anxiety, or substance use disorders. Using logistic regression, we tested the association between psychiatric conditions and CEA/CAS, controlling for demographic, clinical, and hospital factors. Results: Among 37,474 included stroke cases, 6,922 (18.5%) had a psychiatric comorbidity. The presence of any psychiatric condition was associated with lower odds of CEA/CAS (adjusted OR 0.84, 95% CI 0.78-0.90). Schizophrenia/psychoses (OR 0.72, 95% CI 0.55-0.93), depression (OR 0.83, 95% CI 0.75-0.91), and substance use disorders (OR 0.73, 95% CI 0.65-0.83) were each associated with lower odds of CEA/CAS. The association of mental illness and CEA/CAS was dose-dependent: compared to patients without mental illness, patients with multiple psychiatric comorbidities (OR 0.74, 95% CI 0.62-0.87) had lower odds of CEA/CAS than those with only one psychiatric comorbidity (OR 0.86, 95% CI 0.79-0.92; p-value for trend <0.001). Conclusions: The odds of carotid revascularization after stroke is lower in patients with mental illness, particularly those with schizophrenia/psychoses, depression, substance use disorders, and multiple psychiatric diagnoses.