OBJECTIVES: To assess patient emergency department (ED) waiting time, hospitalization rate immediately following ED visit, number of medications prescribed, and length of stay in ED among practices with various levels of electronic health record (EHR) functionality pertaining to mental illness-related ED visits.   METHODS: Data from 2006-2009 Centers for Disease Control and Prevention National Hospital Ambulatory Medical Care Survey ED files were used for this retrospective, cross-sectional study.  Mental disorders were identified via: 1) International Classification of Diseases, Ninth Revision, Clinical Modification codes based on definitions by American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, and 2) mental health-related reason for visits as determined by the National Center for Health Statistics.  EHR use among organizations was classified as no EHR, some EHR, basic EHR, and fully functional EHR based on the number and level of available features.  Negative binomial regression models were applied using waiting time and visit length as outcome variables, while logistic and ordered logistic regression models were applied using hospitalization rate and number of medications prescribed as dependent variables, respectively.  Regression analyses adjusted for patient demographics (age, gender, race/ethnicity, region/location, education, income, insurance status), level of triage and comorbidity, and hospital ownership status.  To provide national estimates, all results were weighted and used standard errors calculated via Taylor-series approaches.    RESULTS: Of the 24.3 million ED visits identified, 37.2%, 33.4%, and 6.0% included some, basic, and fully functional EHRs, respectively.  Having any sort of EHR was associated with 24% greater odds of hospitalization (p=0.032). However, EHR use was not associated with increased wait time (pooled p=0.34), number of medications prescribed (pooled p=0.36), and ED visit length (pooled p=0.30).   CONCLUSIONS: Among patients with mental disorders, EHR may increase short-term health care utilization but benefit patients in the long-term due to early treatment.