PURPOSE: To explore characteristics of patient visits to osteopathic physicians (DOs) and allopathic physicians (MDs) in the provision of ambulatory primary care services at academic health centers (AHCs) relative to non-AHC sites. METHOD: Physicians report patient visits to the National Ambulatory Medical Care Survey (NAMCS). The authors used NAMCS data (2002-2006) to statistically estimate, characterize, and compare patient visits of four physician provider type- and AHC site-specific subgroups: DOs and MDs at non-AHC sites, and DOs and MDs at AHC sites. RESULTS: The 134,369 patient visits reported in the NAMCS database represented 4.57 billion physician office visits after the authors applied patient weights. These visits included 2.03 billion primary care patient visits (205.1 million DO visits and 1.77 billion MD visits at non-AHC sites; 5.8 million DO visits and 52.3 million MD visits at AHC sites). Practicing at an AHC site appeared to change the dynamic of the patient visit to an osteopathic physician. Most notably, these changes involved patient demographics (sex), patient visit context (practice metropolitan statistical area status, patient symptom chronicity, and injury as reason for the visit), and medical management (diagnostic testing, frequency and intensity of ordering drugs, and use of osteopathic manipulative treatment). CONCLUSIONS: Evidence suggests that osteopathic physicians in community, non-AHC settings offer a more distinctive osteopathic approach to primary care than osteopathic physicians at AHC sites, which both indicates a need for further research to explain this phenomenon and has potentially important implications for osteopathic medical education.