OBJECTIVE: To determine whether patients with mental health diagnoses are more likely to utilize home-based primary care (HBPC), and to identify characteristics associated with HBPC admission among elderly and nonelderly veterans, specifically. METHODS: Patients receiving treatment during fiscal year (FY) 2003 and having no evidence of home care utilization during FY2002 were followed through FY2005 using administrative claims data of the Veterans Health Administration of the U.S. Department of Veterans Affairs (VA). Participants were 4,411,677 VA patients with no prior HBPC use. Cox proportional hazard models were developed to identify correlates of HBPC use. RESULTS: Of VA patients with no prior use of HBPC, 24.2% received a mental health diagnosis, of whom 1.5% eventually used HBPC. Two in five new HBPC admissions were diagnosed with mental illness. Patients diagnosed with dementia were 66% more likely to be admitted. Patients diagnosed with nonschizophrenia psychoses (hazard ratio [HR]: 1.30), miscellaneous affective disorders (HR: 1.22), and schizophrenia (HR: 1.21) had the next highest probabilities. Risk of admission was highest for > or = 3 outpatient medical visits (HR: 2.61), followed by any inpatient medical/surgical days (HR: 1.79) or outpatient mental health visits (HR: 1.30). Elderly patients with any inpatient mental health days were less likely to be admitted; younger patients with nursing home use, community residential care, and mental health intensive care management were more likely to be admitted. CONCLUSION: Given that mental illness is independently associated with the likelihood of admission, it is critical that providers develop the skills and resources necessary to meet the psychiatric needs of home care recipients.