OBJECTIVES: Effective and safe oral anticoagulant therapy requires careful dosing, regular monitoring, patient education and frequent follow-up. Antithrombosis clinics (ATC) provide a comprehensive management model. The ATC at the University of Illinois at Chicago Medical Center (UICMC) has been in existence since 1996 and manages approximately 6,500 patient visits per year. The main objective of this study is to evaluate the quality of oral anticoagulation management by assessing the rates of major bleeding, thromboembolic events, hospitalizations, and emergency visits of patients receiving care at the UICMC ATC. METHODS: A retrospective evaluation of medical records from 471 active patients on warfarin therapy managed at UICMC ATC was conducted between September 2002 and December 2006. RESULTS: Data was collected from 471 patients and 958 patient-years of therapy. Females were 67.9% of the cohort, with African Americans representing 57.1%, followed by Hispanics (22.9%) and Caucasians (17.6%). Event rates (expressed as percent per patient-year of therapy) for major bleeding (MB) were 2.3% (1.3% of events occured at INR>4.0; and 1.5% occurred in patients on combination warfarin-antiplatelet therapy). The rate for thromboembolic events (TE) was 2.2% (1.4% occured at INR<1.5). Hospitalizations and ED visits due to non-therapeutic INRs were 0.8% and 1.1%, respectively. The percentage of time in therapeutic range (TTR) for ATC patients was 67.5%. For patients with an event (MB, TE, hospitalizations and ED visits) TTR was only 41.5%. Non-compliance with appointments was 14% for ATC patients overall and 26.5% for those that had an event. No fatal events occurred. CONCLUSION: The quality of oral anticoagulation management at UICMC ATC favorably compares with national benchmark data. Patients with events were more likely to be non-compliant with their visits and spent less time within the therapeutic INR range.