OBJECTIVE: In 2007, the U.S. Department of Veterans Affairs (VA) health system began nationwide implementation of primary care-mental health integration (PC-MHI) programs to enhance mental health access and promote treatment of common mental health conditions for patients in primary care settings. This report describes patients initiating PC-MHI services in fiscal years (FYs) 2008-2010, including those who received prior mental health services. METHODS: Using VA administrative records, the investigators examined characteristics and services utilization of individuals who initiated PC-MHI services in FY 2008 (N=76,985), FY 2009 (N=107,417), or FY 2010 (N=149,938). RESULTS: PC-MHI service initiation increased by 95%, from 76,985 to 149,938 veterans. Over time, new user cohorts were increasingly younger, newer to VA services, and less likely to have received VA mental health treatment in the prior year. CONCLUSIONS: This study documents substantial expansion in VA PC-MHI program activity. PC-MHI program expansion may increase access to mental health services in primary care settings.